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Using Praat for Linguistic Research

1. 0 504 5000 T E 3 z o 2 HH r tail 000101 0 0 7134 Time s 0 519 0 0 7134 anne Time s gt a Pitch with intensity in blue gt 7500 3 a 3 a 3 H E a E 0 E a epee aks 0 0 7134 42 0 Time s 0 0 7134 Time s Figure 12 You can now combine overlay and juxtapose plots of excess as in the above single Praat picture 47 TextGrid annotations are composed of different tiers which mark either intervals or specific points within the sound file Interval tiers are designed to mark elements of a file with a distinct span like a vowel word or segment Point tiers mark single points like release bursts turn changes or glottal openings Both intervals and points can and should be labeled The names and relative position of these tiers are specified when the TextGrid is created It s worth noting that Praat counts EVERY interval in the file not just human created or labeled ones so if you mark and label a single vowel interval in a file Praat will consider the file to have three intervals the section before the start of the vowel the marked vowel and the section after the vowel The marked vowel in this situation would be considered interval number 2 To create a TextGrid for a sound file 1 Open and then select the sound that you want to TextGrid 2 Objects Annotate To TextGrid 3 Name your tiers s
2. Much like a movie script tells a set of actors exactly what to say and what actions to take a Praat script is a text file which tells Praat exactly what to do and walks the program through a series of steps Anything that you can do through the GUI of the program GUI is graphical user interface the menus and buttons you use to interact with Praat you can command Praat to do in a script Praat scripting is a wonderful tool then for situations where you find yourself repetitively doing the same tasks over and over again and with increased sophistication you can have Praat make simple decisions based on its measurements and changes Simply put Praat scripting is a way to use the computer as a co pilot handling the boring repetitive tasks independently and allowing you to do your job more efficiently Praat scripts can be as simple as a single line which tells Praat to adjust the Spectrogram settings to display a narrowband spectrogram or as complicated as 500 lines of code which allow Praat to go through a folder of files measuring A1 PO nasality for each file and presenting any suspect measurements for human confirmation 52 Here s a very basic Praat script which shows a series of commands to Praat with commented lines prefaced with to explain what it s doing This is a comment Praat ignores lines that start with select Sound untitled Plays the sound Play Gets the duration Get total duration Get
3. Query Query Time Domain Get Total Duration Now let s get the average height of F and F of the sound 6 Select the sound 7 Objects Formants amp LPC To Formant burg e This creates a formant object that we can get the mean formant values from 8 Select the new formant object 9 Objects Query To mean e This measures the mean for a given formant Repeat this for Formants 1 and 2 Now let s reap what we ve sown 1 Go back to your Script Editor window 2 Script Editor Edit Paste history If all went to plan your Script Editor window will have something like the code pictured be low Code generated from the above process Edit Extract selected sound time from 0 Close Get total duration To Formant burg 0 5 5500 0 025 50 Get mean 1 0 0 Hertz Get mean 2 0 0 Hertz Each of those lines are the Praat script commands to do each of the tasks To Formant burg 0 5 5500 0 025 50 turns a sound into a Formant object with the settings specified in the trail ing numbers Get mean 10 0 Hertz intuitively enough gets the mean of the formant specified in the first number in the time range specified by the next two 0 all and gives it in Hertz as opposed to Bark Note though that because you used the mouse to do the selection instead of using the commands in the Editor Select menu the exact definition of the selection doesn t show up In short this is th
4. Also you can create more than one graphic per picture window just change the selection area 3 Select the newly created Spectrogram object then Objects Draw Paint e Set these parameters as you d like 4 Use the Picture Margins menu to add labels text and other garnishes 5 Use Picture File Save as PDF file to export your picture e Be warned the resulting PDFs will have very large file sizes as they capture a great deal of detail As such they can be expanded and shrunken quite gracefully There is obviously much more complexity possible but repeating and adapting the steps will yield wonderful graphs for any publication This entire process is quite easily scriptable as well For additional information about using Praat pictures consult Jennifer Smith s wonderful Print ing and copying pasting Praat Images handout available at http www unc edu j lsmith ling120 pdf 5images pdf 43 Fil a arcing world Select Pen Font Figure 10 The Praat Picture Window 44 Waveform C 0 754 0 54 0 254 0 254 0 54 0 754 O 0 005 001 0 015 0 02 0 025 0 03 0 035 0 04 0 045 0 05 Time s Figure 11 An example of an exported garnished waveform plot of a 400 Hz pure tone By creating sounds from formula see Section and combining them together using waveform addition and subtraction see Section 7 10 it s a breeze to create the sorts of lightweight yet accur
5. Number is odd 73 11 4 8 Everything Else Praat scripting takes a long time to really get your mind around and there are all sorts of other constructs which can be useful in working You would be well served once you ve got your mind wrapped around the basics to examine the Praat Scripting tutorial pages Objects gt Help Praat Intro Scripting for some of the following concepts which will improve your scripting efficiency even more e Scripting 5 3 Jumps This section talks about using elsif and else to improve your script s flow e Scripting 5 5 Procedures This section talks about using Procedures to streamline your code and minimize repetition e Scripting 6 6 Controlling the User This section talks about using Pause forms to ask the user questions and to confirm measurements e Scripting 7 7 Scripting the Editor This section will teach you how to work within the editor window in Praat scripts 11 5 In defense of Code Cannibalism There is very seldom any need to reinvent the wheel and there is no shortage whatsoever of Praat scripts available online and floating around departments Although it s unlikely that you ll happen to find a script which does exactly what you need chances are very good that what you need can be cobbled together from several scripts So long as you give attribution to the original author s of the script s you borrow code from there s no shame in reusing par
6. if F 2600 Hz at the cursor once this command is run the variable f3height will be equal to 2600 Then you ll use that number in the formula above to calculate a new variable the length of the vocal tract Remember having run the first command f3height will now be equal to the height of F3 Praat is perfectly capable of doing basic math so we can hard code the other parts of the equation into the script length 2 3 1 343 4 x f3height This will assign the output of 2 3 1 343 4 f3height tothe variable length Finally you ll want to convert the output length which is currently in meters to a more useful unit namely centimeters lengthcm length 100 Then you ll need to display this information in an information window To do that use the print command print Your vocal tract length is lengthcm 1 cm This command will print the sentence Your vocal tract length is followed by the lengthcm variable s contents followed by cm The 1 attached to Lengthcm rounds the output down to one decimal point Put together this is your entire script f3height Get third formant length 2 3 1 343 4 f3height lengthcm length 100 print Your vocal tract length is lengthcm 1 cm You would then save the script and either open it as an Editor script because it relies on the mouse cursor within the editor window when getting the third formant or add to a menu i
7. sample would then be set to an amplitude of zero and the resulting file would be completely silent e 4 If you just put a 4 into the formula box Praat would read this as the amplitude of the sample in question in the selected sound equals 4 self col 4 Every sample would then be set to an amplitude of 4 and the resulting file would be constantly at four and would likely stress or damage your headphones or speakers if played loudly e self col Praat would read this as the amplitude of the sample in question in the selected sound equals the amplitude of the sample in question in the selected sound self col self col As such it would not modify the sound in any way and would be a rather complete waste of your time x In formulas you ll refer to sound col frequently which just means each in 39 dividual sample in the sound self is the sound selected when you opened the formula window e self col 2 Praat would read this as the amplitude of the sample in question in the selected sound equals two times the amplitude of the sample in question in the selected sound self col self col 2 This formula would double the amplitude of every sample making the sound file twice as loud e Sound_soundb col Praat would read this as the amplitude of the sample in question in the selected sound equals the amplitude of the sample in question in the sound file called soundb This formul
8. t 3 Praat will calculate the frequency of the sound in Hertz in the top bar giving it in the format ___ s Use the zoom sel button to zoom in if you can t see the frequency readout This is going to be an accurate number so long as you gave an accurate period but you re welcome to calculate it yourself to make sure f 2 where t is the period in seconds 15 6 4 2 Viewing Pitch via a narrowband spectrogram The most reliable way of getting a sense of the pitch through the course of the word in Praat is by examining a narrowband spectrogram with a reduced visible range 0 400 Hz for speech This can be done by editing the spectrogram settings as described in Section 6 2 The contours of the harmonics will accurately represent the pitch contours of the voice during the word and doing this will give you a sense of the contour before using the Praat pitch tracker for more precise measurement 6 4 3 Using Praat s Pitch Tracking Praat does have the ability to provide a pitch track in the editor window To enable the pitch track in the Editor window Editor Pitch Show Pitch At this point a blue line will be placed on top of the spectrogram representing the pitch where Praat can find it Once the pitch track is placed you can use the cursor to check the pitch at any given point in the word Just place the cursor and look for the middle blue number on the right side of the window You can also place your cu
9. 2 Praat scripts vs Editor scripts 11 2 Working with Scripts 11 2 1 Opening and running a Praat script 11 2 2 Making and removing Menu Shortcuts for scripts 11 3 Creating a new script 11 3 1 Using other text editors 11 3 2 Filenames 11 3 3 A Note on Praat Script Commands w 29 29 30 31 32 32 33 33 34 34 36 37 37 38 41 41 43 45 45 46 46 49 11 3 4 How to magically write a Praat script using the Praat history function 60 11 3 5 Writing your first single command script 62 dea hE ese ha he ee ee Sek eG Seen a wee 63 A ate 65 RR 65 EPA MENtS os oe sees Goes e EE wT S ake AOS a Gade MA era eae 66 Yas Rw ee sek ira eee pha soe ew ge aaa e 67 T1244 FOPMS gt saia wee gw we We ee GR ws we wR es 67 11 4 5 Commented lines 0 000 0 0000 eee ee ee eee 71 11 4 6 Scaling scripts up nowarn noprogress and avoiding the editor window 71 11 4 7 Useful tips 2 ne 72 11 48 Everything Else aco ok ee ee a eae ee eS Page eka kd 74 11 5 In defense of Code Cannibalism 000002 eee 74 11 6 Closing Remarks on Praat scripting oo ooo oo eee 75 Version History e 1 4 5 March 6 2014 Made a number of clarifications improvements fixes and updates to the scripting section based on wonderful feedback from Jos Joaqu n Atria Thanks Jos Also added brie
10. Move start of selection to nearest zero crossing or Cmd Editor Select Move end of selection to nearest zero crossing or Cmd 2 3 4 Editor Edit Copy or Cmd c 5 Put the cursor where you d like the portion to go 6 Editor Select Move cursor to nearest zero crossing or Cmd 0 30 7 Editor Edit Paste or Cmd p Following these steps will cleanly insert the snippet into the word Given time you ll develop muscle memory and find yourself quickly typing Cmd Cmd Cmd c to copy and Cmd 0 Cmd p to paste Copy pasting can be done either within the same file or between two different files in Praat This can also be done from the objects window using Objects Convert Extract Part To delete a portion of a file or to remove silence you ll select again attending to zero crossings and use the Cut command without pasting anywhere else To delete a portion of the soundfile 1 Select the portion of your soundfile that you d like to disappear 2 Editor Select Move start of selection to nearest zero crossing Cmd 3 Editor Select gt Move end of selection to nearest zero crossing or Cmd 4 Editor Edit Cut or Cmd X Unfortunately Praat doesn t include an easy way to trim splice or cut portions of the file from the objects window meaning that any scripts will have to use GUI scripting the computer controlling the mouse selection tool on the
11. Onset Time 1 1 1 January 2nd 2012 A few other small corrections based on Paul Boersma s feed back 1 1 January 1st 2012 Updated with Paul Boersma s valuable feedback and a variety of small corrections 1 0 2 July 14th 2011 Removed some typoes and fixed other small issues 1 0 1 July 10th 2011 Updated to include instructions on removing scripts from But tons 1 0 July 10th 2011 Version created for LSA Institute Workshop on Praat 2 Introduction Praat is a wonderful software package written and maintained by Paul Boersma and David Weenink of the University of Amsterdam Available for free with open source code there is simply no better package for linguists to use in analyzing speech Unfortunately much of the existing documentation for the software is just that software docu mentation and is not designed to help linguists who may not necessarily consider themselves to be phoneticians or have a strong phonetics background get the measurements and make the changes that they need and desire for their research As such rather than introducing each menu item and function as such I ve instead chosen to describe how to do some of the tasks that linguists want to do without assuming a strong phonetics or programming background Then eventually we ll discuss some of the more com plicated measures and tricks one can perform with Praat Of course no one workshop can discuss the myriad of feature
12. Will Styler Establishing the Nature of Context in Speaker Vowel Space Normalization vol MA University of Colorado at Boulder Boulder CO April 2008 76
13. if vowel_label i Set interval text 2 2 HighFrontVowel elsif vowel_label u Set interval text 2 2 HighBackVowel else Set interval text 2 2 SomeOtherVowel endif 66 For much of its life Praat script used lt gt to mean not equal to rather than the usual or or Although recent versions mercifully allow the far more es common to mean the same thing be aware that older scripts will still include this Danger odd lt gt notation 11 4 3 while loops while loops are meant to tell Praat to continue doing something until a certain condition is met Let s say you wanted to add a second sound to a first sound over and over again until it was 3 seconds long select Sound soundname _original while chunk_duration lt 3 plus Sound soundname _addition Concatenate chunk _duration Get total duration endwhile Here a while loop is ideal as it just keeps going until the criterion is reached with no further code muss or fuss While loops are great but Praat especially on OS X acts funny if it has to do more than a certain number of iterations as they can quickly fill up your mem os ory Especially if your while loop deals with something complex which might not always happen if Praat starts crashing on certain tokens your while loops are a Danger good place to start looking 11 4 4 Forms Forms can run either at the start of the script or during the script i
14. in Section 7 2 Mac users this is a non issue if you have a 64 bit Mac and download a recent 64 bit build for Os x 5 2 Saving Files Praat does not save anything by default and until you save files explicitly opened or edited ver sions of the files will exist fleetingly in the objects window For emphasis unless you save files explicitly they will disappear completely and unrecoverably when Praat is closed To save a file select the file in the Objects window then Objects Save Save as file For sound files you ll likely choose Save as WAV file but for the other types of files TextGrids formant objects pitch objects etc you ll save them as text files As this can be very tedious you might consider downloading and installing a Praat script see Section 11 which saves all the objects in the objects window at once 10 ano 2 Sound untitled I j File Edit Query View Select Spectrum Pitch Intensity Formant Pulses Help MI Group Figure 2 The Praat Editor Window 6 Phonetic Measurement and Analysis in Praat 6 1 Working with Praat Waveforms and Spectrograms Once a sound has been recorded or opened you ll spend much of your time interacting with the sound by means of the Editor window To open a sound in the editor window select the sound and then Objects View amp Edit You re immediately presented with an editor window like that in Figurel2 showing the wave fo
15. in a person s voice is how much one period differs from the next in the speech signal This is a useful measure in speech pathology as pathological voices will often have a higher jitter than healthy voices Shimmer amplitude perturbation is similar to jitter but instead of looking at periodicity it measures the difference in amplitude from cycle to cycle Once again this is a useful measure in speech pathology as pathological voices will often have a higher shimmer than healthy voices Harmonics to noise ratio HNR and Noise to harmonics ratio are both measures of the amount of periodic noise compared to the amount of irregular aperiodic noise in the voicing signal Because the aperiodic noise often represents frication in the vocal tract the HNR will go down significantly with hoarse or breathy speech and other laryngeal pathologies will lower the HNR further still 6 6 Measuring Formants Praat has several methods of built in formant measurement Of course the easiest way to examine formant heights is by simply looking at a broad band spectrogram and using the cursor to find roughly their frequencies However eyeballing it won t pass scientific muster and is more time consuming than using Praat s built in LPC algorithms as a tool to help to find them 6 6 1 Using the Formant tools in the Editor window When you open a sound file in the Editor window you can choose to have Praat calculate and display where it thinks tha
16. range controls how much of the spectrum is visible For speech you ll likely be interested in the range from 0 to 5000 or 6000 Hz but if you re examining fricatives you might want to look as high as 15 000 Hz If you re looking at music you may focus on the area from 100 to 2000 Hz Either way this is how you set which part of the spectrum you care about If your sound files have a relatively small or large dynamic range the difference in volume between the loudest and quietest parts or if your spectrograms seems too light or too dark you may want to adjust the dynamic range setting here but 50 dB is usually safe Window length given in seconds controls how large of a chunk of the sound Praat will examine when trying to find the frequencies present at a given moment in the signal Looking at a larger window of the sound will give more accurate information about the frequencies present but will also reduce the accuracy of the temporal information given Varying the window length allows you to choose between Broadband and Narrowband spectrograms 13 6 2 1 Narrowband vs Broadband Spectrograms Praat defaults to showing a Broadband spectrogram which is excellent for viewing the temporal structure of the sound and for seeing vowel formants but sometimes you ll want to look at harmonics and Fo instead To do this you ll ask Praat to provide you with a narrowband spectrogram To do this 1 Editor Spectrum Spectrogram Setti
17. sound file we ll call it vowela e Any vowel will do 2 Select that vowel then Objects gt Formants amp LPC To LPC e Choose whatever algorithm you prefer Burg is my personal favorite 3 Select both the vowel and the LPC object that s been created Sound vowela and LPC vowela then Objects Filter inverse e This will create the neutral source voicing from that vowel 4 Select the LPC then Objects To Formant e Praat won t let you edit an LPC object but you can easily edit a formula object 5 To change formant frequencies select the Formant object then Objects Modify For mula frequencies e You ll edit this by formula see Section 7 10 but it will always have the form if row formant number then self modification else self fi So if row 1 then self 100 else self fi would raise the first formant by 100 Hz e Changes less than 20 Hz are unlikely to work well and changes more than 200 Hz won t work either When making changes here and while scripting large changes should be done in 50 Hz steps rather than all at once repeating the 50 Hz change as many times as needed 6 To change formant bandwidths select the Formant object and the source generated in step 3 and Objects Filter This will output your new vowel ideally with the new formants That said this is a very finicky process with lots of room for error and it will require some work to get working cleanly Thi
18. the new format but anything you see here still works if dropped into a script That said new style commands will cause scripts to crash in older versions of Praat This is yet an other reason to download the newest version of Praat every time you start a new project 11 3 4 How to magically write a Praat script using the Praat history function Praat scripting relies on Commands which are effectively verbs which describe the actions Praat should take These commands can take a variety of forms but they usually start with an uppercase letter or in newer versions Do Here are a bunch of Praat commands selected randomly from several scripts Rename Extract part Get starting point select Get high index To Manipulation 0 01 75 600 Get first formant Get frequency of maximum Erase all and many many more The most beautiful part of Praat scripting comes with the realization that if you can do some thing through the GUI Praat will magically give you the exact commands to do it by script Let s examine this wonderful reality by unintentionally writing a Praat script using Praat s history function First let s do a little bit of work in Praat to simulate doing phonetic research 1 Open a sound and extract the vowel 2 Praat Menu New Praat Script 3 Script Editor Edit Clear history Now let s get the duration of the sound 4 Select the sound 60 5 Objects
19. the script is do not need to change across platforms For instance so if you included the below directory assignments in your script e directory test data or e directory test data Praat would always look for data in a folder called test data in the same folder as the script itself This script would function well on any operating system provided the data is put in the proper folderl d Incorrectly formatted absolute path names are the most common issue which pre vents you from running scripts you download from the internet If your script e S won t run check the file paths throughout the script and update them to match Danger your operating system 11 3 3 A Note on Praat Script Commands In the Summer and Fall of 2013 Paul Boersma has updated the Praat script language chang ing the syntax of some of the commands to be more familiar to people working with other programming languages Although the old commands as shown in the manual do still work new commands generated by the the process will look like do To Manipulation 0 01 75 600 versus the old command format Thanks to Paul Boersma for pointing out this particular tip 59 To Manipulation 0 01 75 600 Don t be alarmed if you see this new format It s fairly straightforward to convert between the two formats mentally and old commands do still work I have not had the time to update all of the code in the manual for
20. the sound to an intensity object Objects To Intensity Then select the intensity object and run Objects Query Get mean This will return values in dB as desired Similarly if scripting this process select Sound soundname min do Get minimum 0 0 Sinc70 max do Get maximum 0 0 Sinc70 mean do Get mean 0 0 0 Will yield min max and mean intensity measurements in Pascal whereas select Sound soundname do To Intensity 100 0 yes min do Get minimum 0 0 Parabolic max do Get maximum 0 0 Parabolic mean do Get mean 0 0 energy Will yield measurements in dB 6 8 Working with Spectra Sometimes you need specific details about the frequencies and individual harmonics in a sound at a given moment in time and examining a narrowband spectrogram alone does not provide 23 sufficient information In these cases you ll need to take a spectral slice for analysis Spectral slices also referred to as FFTs or spectra are the result of a fast fourier transform done on a very small portion of the sound providing you with very specific information about the frequencies present in the sound and their relative amplitudes Spectral slices are useful for a variety of measures of Fo nasality creak breathiness and spec tral tilt and are a crucial part of many measurement workflows 6 9 Taking a spectral slice To ta
21. you to swap the pitch tiers of sound files which are not the same length Select Sound B Objects To Manipulation e Leave Time Step unchanged e Set the pitch range to whatever is reasonable for that speaker Usually 75 300 Hz works fine Select the newly created Manipulation B then Objects View amp Edit 5 Select Sound B Objects Extract Pitch Tier e This will give you PitchTier B Now select Sound A Objects To Manipulation e Leave Time Step unchanged 35 e Set the pitch range to whatever is reasonable for that speaker Usually 75 300 Hz works fine 7 Select the newly created Manipulation A as well as PitchTier B 8 Objects Replace Pitch Tier 9 Select Manipulation A which you just combined with PitchTier B then Objects View amp Edit 10 In the Manipulation Window Manipulation File Publish Resynthesis 11 This will export a copy of the finished version into the Objects window Save it from there Praat s pitch matching feature is only as effective as its pitch tracking feature which means that both are suspect Although the two sounds pitch tracks will be signifi os cantly closer following this step they will not be identical and there may be artifacts and odd jumps left over If you require the sounds to be exactly matched match them D anes both to a completely flat pitch generated by formula see Section 7 1 7 7 Manipulating Duration
22. Editor window telling the Editor what to select then to cut etc This works well but is slightly less efficient than is desirable Some progress can be made from the Objects window alone by using a combination of Objects Convert gt Extract Part and Objects gt Combine Concatenate to effectively create new sounds which resemble a cut or trimmed sound but this can be quite counterintuitive If Praat won t let you copy and paste a chunk between two files the files may need to be resampled to match 7 3 Sampling rates and Resampling Praat is very picky about the sampling rates of the files it works with When combining sounds or copy pasting from one file to another both sounds will need to have the same sampling rate To get the sampling rate of an existing file 1 Load the sound into the objects window of Praat 2 Objects Query Query Time Sampling Get Sampling Frequency 3 An info window will pop up displaying the sampling rate 31 To resample a soundfile e g change the sampling rate from 44 100 Hz to 22 050 Hz 1 Load the sound into the objects window of Praat 2 Objects Convert Resample e New Sampling Frequency 22050 or whatever sampling rate you d like e Precision Samples 50 don t change this number 3 The filtered sound will be placed into your Objects window as Sound soundname_ new sampling rate 7 4 Filtering Sounds Not all changes you ll want to make involve parts o
23. Objects window to be saved as usual Note as well that Praat can use either LPC resynthesis discussed later or overlap add resyn thesis to create the file Overlap add is actually PSOLA Pitch Synchronous Overlap Add Method resynthesis and will almost always produce more natural results 7 6 Matching the pitch tracks of two sounds When combining sounds or creating perception experiment stimuli it can be useful to match the pitch contours of two sounds Although one can attempt this in the Manipulation win dow as described above it s far easier to use the below procedure to match the pitch track automatically 34 LOO aon i a 8 Mani ith T A a E T Freri File Edit Query View Select Pulse Pitch Dur Synth Help On bee leh eM 1 000 126 1 C a a a 0 7893 es Pitch manip 604 4 Hz vasoseaeasaeesodoseovovososvavasasesoavavesosssvacavososoavacosodoseavasosesvavasesoncavavososesoatason gt ones sesessavavaneser wesenvaravacenes ones sesenvavavaneser enon eee ones sesessavarasaser sonenvaravecener 195 0 Hz i Duration manip 3 000 no duration points GID Cin Cout Gel ak Group Figure 8 The Praat Manipulation Window To give Sound A the same pitch pattern as Sound B 1 2 Load both Sound A and Sound B into the objects window of Praat Trim either Sound A or Sound B so that they have exactly the same duration e Praat will not allow
24. Slowing Down and Speeding Up Sounds Similar to modifying pitch in existing sound files Praat allows you to modify durations result ing in sped up or slowed down sections of existing files First again you ll need to create a manipulation object To create a manipulation object which allows you to change a sound s pitch and duration 1 Load the sound into the objects window of Praat 2 Objects To Manipulation e Leave Time Step unchanged e Set the pitch range to 75 600 Hz 3 Select the newly created Manipulation Soundname then Objects View amp Edit This will open a manipulation window like the one shown in Figure 8 You ll notice that un derneath the pitch manipulation area there s a small bar labeled Duration Manip which starts off saying no duration points To speed up or slow down a sound file 1 Dur gt Add Duration Point at Cursor 36 e Although it says at cursor adding just one point allows you to manipulate duration for the whole file 2 Now drag that single duration point up or down in the Duration Manip area to change the speed of the file e Dragging the point up increases the duration slowing the sound down dragging it down decreases duration and speeds the sound up You can add multiple points and selectively speed or slow certain parts of the recording to change the length of a vowel for instance In addition as before Praat can export the file to a wav file which is be
25. Using Praat for Linguistic Research Will Styler University of Colorado at Boulder Phonetics Lab Document Version 1 4 5 Last Update March 6 2014 Important This document will be continually updated and improved Download the latest version at http savethevowels org praat Using Praat for Linguistic Research by Will Styler is licensed under a Creative Commons Attribution ShareAlike 3 0 Unported License For more information on the specifics of this license go to http creativecommons org licenses by sa 3 0 Contents 1 Version History 3 2 1 Versions 2 0 0 ee ee eee 2 2 Other Resources 2 0 eee ee eee ee ee ee eee eee 2 3 Getting and Installing Praat ee ee ee About Praat 3 1 Praat Windows ea ss xo hkl a Sk we WE Re we wa Ak ee a 4 Recording Sounds 5 6 Opening and Saving Files LEGA AREER PEROT SRE ESOS OEE BS oe bees POR ERA O AAA AE AAA Phonetic Measurement and Analysis in Praat ee PAE E A eae ee reia A a ica 6 3 1 Measuring Voice Onset Time VOT 6 4 Examining and measuring F Pitch 6 4 1 Measuring Fo from a single Cycle ooo ooooo o 6 4 2 Viewing Pitch via a narrowband spectrogram 6 4 3 Using Praat s Pitch Trackingl o o eee curada 6 4 5 Scripting only Creating a Pitch Object o oo o EE A E a a a ro Ms he spe Me tie EE E E EE hg A 6 7 1 Units of Intensi
26. Yet another request from the user but here with a choice 2 is default mode _ Model Mode2 This choice is boolean Yes vs No and defaults to yes M ScriptisAwesome Standards _ Cancel Apply OKs Figure 16 A form generated with the demo form code above text directory your suggestion for what they type in comment Another request but this lets them assign a number for each choice integer vowel 1 integer word 2 comment Yet another request from the user but here with a choice 2 is default choice mode 2 button Model button Mode2 comment This choice is boolean Yes vs No and defaults to yes boolean ScriptIsAwesome Yes endform This code would create a form like below in Figure 16 You could then use that form s choices to make decisions later if mode 1 print Your mode is set to 1 elsif mode 2 print Your mode is set to 2 endif if ScriptIsAwesome print You re awesome 69 else print Someday you ll be awesome endif 70 11 4 5 Commented lines Not every part of a Praat script is designed to be read by a computer Lines which start with a symbol are called Commented Lines and will be ignored by Praat They re usually written in by human programmers to explain exactly what the code is doing or in some cases as a header Do yourself a favor and comment the code that you write as sometimes it s the only way you ll understand your code when you look at it day
27. a would turn sounda into a sample by sample copy of soundb x Note that in formulas other sounds in the object window need to be referred to as Sound_soundname not just soundname e self col Sound_soundb col Praat would read this as the amplitude of the sample in question in the selected sound equals the amplitude of the sample in question in the selected sound plus the amplitude of the sample in question in the sound file called soundb This formula would add sounda and soundb using waveform addition x When adding subtracting or multiplying sounds you ll usually want to match the resulting sound s amplitude to that of the original sound afterwards see sec tion 7 8 e self col Sound_soundb col Praat would read this as the amplitude of the sample in question in the selected sound equals the amplitude of the sample in question in the selected sound minus the amplitude of the sample in question in the sound file called soundb This formula would subtract soundb from sounda using waveform subtraction e self col 2 Sound_soundb col This formula would add twice the amplitude of soundb to sounda using wave form addition Such a formula would be useful for combining two sounds when you want the acoustical features of one sound to slightly overwhelm those of the other Using the above as a template you can create a formula to do nearly anything you d like to your sound waveform both throug
28. anger ek ie immediate indication how a given chunk of code was meant to be run 11 2 Working with Scripts Because a Praat script is literally just a text file with a series of commands to Praat they can be found all over the internet and can be saved as a plaintext file it s best to give it the praat suffix if nothing else for your own reference Praat scripts can be run in two distinct ways 11 2 1 Opening and running a Praat script To open a Praat script in Praat and then run it 1 Praat Menu Open Praat Script e This will open the script in a Script Editor window where it can be viewed or edited To open an Editor script in Praat and then run it 1 Open the sound you re interested in in the Editor window 2 Editor File Open Editor Script e This will open the script in a Script Editor window where it can be viewed or edited To run a script either Editor or Praat scripts 1 Script Editor gt Run Run or Cmd r Ctrl r on Windows Note that if you just want to run a small part of the script useful when cannibalizing scripts for certain functions you can select the part in question and use Script Editor gt Run Run Selection 55 11 2 2 Making and removing Menu Shortcuts for scripts Sometimes you ll want frequent access to a Script without having to find it open it then click Run To do this you can add the script to a menu There are two options on how to do thid Firs
29. ast polished of Praat s features but don t let that scare you off To do any formula modification 1 Load the sound s you d like to modify into the objects window of Praat 2 Select the sound you d like to modify e Remember this will modify the existing sound not create a modified copy so make sure to make a copy of the sound to work on 3 Objects Modify Formula This will then pull up a very technical looking input box pictured in Figure 9 To actually make the combination you ll need to put into that box the formula which will be applied to the 38 BOO i l Sound Formula 1 x is the time in seconds col is the sample number x x1 time associated with first sample for col from 1 to ncol self col e x x dx endfor Help Standards Cancel Apply a Figure 9 The Praat Formula Modification Window amplitude value of each individual sample To make this process a bit more clear let s imagine that we ve got a file called sounda and a file called soundb in our Objects window You ve gone through made a copy of sounda to work on selected that copy and then Objects Modify Formula Here are several formulas you could put into that window and the effect that each of them would have 0 If you just put a O into the formula box Praat would read this as the amplitude of the sample in question in the selected sound equals 0 self col 0 Every
30. ate waveform graphs needed when teaching and m i testing students on the fundamentals of acoustics and waveform addition onus 8 1 Creating Complex Displays Using the Praat picture window as a canvas you can add more detail to a graph than is avail able from a single command by overlaying plots and combining multiple plots into a larger layout 8 1 1 Overlaying Plots You can use the Praat picture window to generate plots with multiple data types on them at once For instance if you wanted to overlay a pitch trace onto a spectrogram you would simply draw a spectrogram as above and then without changing your selection in the window create a pitch object and draw it with the same Time boundaries as for the spectrogram Although it may not always make sense to do so you use a series of draw commands to overlay any graphics To do this complete the same steps above and then repeat the draw process for each element changing the color and width of lines using Picture Pen before each draw to help multiple plots stay distinguishable 45 Doing this you can represent as many different types of data on a single plot as you d like up to and well beyond the possibility of any readability 8 1 2 Multiple Plots in the Picture Window Similarly if you wanted to draw a waveform above a spectrogram in the picture window sim ilar to the editor display you would 1 Select the portion of the picture window which will have your wa
31. cy 2000 or whatever you d like your highest frequency sound to be e Smoothing 20 Hz 20 Hz is a good baseline This controls how soft the cutoff is 5 Hz is as low as you ll ever want to go for this setting 3 The filtered sound will be placed into your Objects window as Sound soundname_band 7 4 3 Band pass notch filtering Band pass filters also called Notch filters are useful for removing sound in a very specific band of the spectrum Notch filters are best suited for removing particular background noises with specific frequencies e g computer fans mains hum or chair squeaking Your bands will be wider or narrower depending on the signal you re working to cut out To band pass filter a soundfile e g removing all sound between 1500 and 3500 Hz 1 Load the sound into the objects window of Praat 2 Objects Filter Filter Stop Hann Band e From Frequency 1500 e To Frequency 3500 or whatever you d like your highest frequency sound to be e Smoothing 20 Hz 20 Hz is a good baseline This controls how soft the cutoff is 5 Hz is as low as you ll ever want to go for this setting 3 The filtered sound will be placed into your Objects window as Sound soundname_band Finally note the Objects Filter Filter Formula option which lets you filter sounds in a much more specific way than the two options above provide 33 7 5 Pitch Manipulation To Manipulation Praat does allow you to ma
32. ditory Phonetics Keith Johnson provides a formula to calculate the length of person s vocal tract based on any formant of a neutral vowel He gives this formula as L 2n 1 c 4F L Length in Meters n Formant Num c the speed of sound in air 343 m s Let s say you want to calculate this more often and grow tired of manually calculating it Instead you d like to be able to record a neutral vowel then calculate the length based on F3 at the cursor s location First you ll need to capture the F value at the cursor By using the history command you ll find that the command for getting F3 at the cursor is Get third formant However this normally just pops the output of the command the F height into an info win dow Because we need that information to be accessible to the script we need to capture it as a variable Although Praat s tutorial on Scripting has a wonderful section on Variables and you should really read through that to get a full idea in Praat capturing the output of a command as a variable is easy To assign a variable to the output of a command you just name the variable then put an equals sign then the command whose output you want to capture like so Thanks yet again to Dr Rebecca Scarborough for portions of this text 63 variable commandtogetoutput Or in our case f3height Get third formant The above line will then capture the output of Get third formant and store it So
33. e kernel of a Praat script that does everything you just did and this is one of the most effective ways of figuring out what commands to use in your Praat scripting The process is always the same 1 Open the Script Editor 61 2 Script Editor Edit Clear history 3 Do using the interface whatever actions you d like to get the script commands for 4 Script Editor Edit Paste history By doing this you ll be able to see how to command Praat to do anything that you can do in the GUI 11 3 5 Writing your first single command script Praat scripts can run the gamut between massive 800 line programs and single function single line editor scripts Although the massive programs are often flashiest in many cases the single item scripts are the ones you can t live without First let s write a script which will turn the Spectrogram displayed in the editor window into a Narrowband spectrogram as described in Section 6 2 1 using the history function To do this 1 Open a sound in the Editor window Open the Script Editor and create a new script Script Editor Edit Clear history Editor Spectrum Spectrogram Settings Set the Window Length to 0 025 or the narrowband window length of your choosing D HO A W N Go back to the Script Editor window then Script Editor Edit Paste history 7 Save the script wherever you d like using Script Editor File Save The resulting scr
34. e speakers lowest Fy and the maximum to just over their highest pitch excursion Changing the minimum pitch will also change the smoothing of the intensity line when displayed e Unit Here you can choose your unit of choice for the display of the speaker s Fp ranging from Hertz to Semitones to auditory scaled measures like logHz or mel e Method You ll usually keep this parameter set to autocorrelation but you can switch to cross correlation to see if it improves your pitch track You may want to tweak the advanced settings as well To do so Editor Pitch Advanced Pitch Settings Then adjust the settings as follows e Silence threshold This is the amplitude threshold for what Praat considers to be speech relative to the peak amplitude in a file If Praat can t find ANY pitch in a quiet file adjust this setting e Voicing threshold Praat uses this value in its algorithm to help it decide whether voicing is present If Praat is finding voiceless portions of the word as voiced raise this number If Praat isn t detecting voicing that s there in the signal lower it This is mostly important when working with data with either very large or very small amounts of background noise and can often be left alone e Octave Jump cost Changing this value affects the algorithm s decision about whether a jump in Fo is reasonable Larger values disfavor abrupt changes in Fp Increase this number if
35. e through your 49 li AIDA y INN L A AN Figure 14 A completed TextGrid annotation showing Vowel and Word tiers 50 data using log files which are then easily exported into Excel or the statistics program of your choosing This is useful when doing a series of repetitive measures which still require human intervention but in many cases the use of Praat scripting can speed this process up further and in some cases eliminate the need for human intervention altogether To create and use a log filef 1 Open a sound in the Editor window 2 Editor gt Query Log Settings a Choose a location and file name for Log file 1 or Log file 2 e On a Windows machine this will look like C Documents and Settings All Users Desktop Log txt e Ona Mac this will look like Users yourname Desktop log txt b Fill in Log 1 Format and or Log 2 Format according to what you d like to measure e For duration include the single quotes t1 4 tab t2 4 tab dur 6 This will give you the start time t1 and end time t2 of a selection and its duration dur The numbers after the colons specify the number of decimal places e For formants include the single quotes t1 4 tab f1 0 tab f2 0 tab f3 0 This will give you the start time t1 and first three formant frequencies f1 f2 f3 at the cursor point li
36. ech This is easy 1 Select the portion of the sound for which you d like the Maximum Minimum or Average Pitch 2 Select the proper command for your task from the Editor Pitch menu Note that Editor Pulses Voice Report will give this information as well 6 5 Measuring Pulses Jitter Shimmer and Harmonics to noise ratio As a part of its pitch handling system Praat includes the ability to find individual glottal pulses in a signal and to analyze the pulses as part of more complex analyses To view these pulses Editor Pulses Show Pulses and they ll then display on top of the waveform in your file Al though the pulses themselves are mostly only useful in scripting the Editor Pulses menu con tains one of the more useful commands in the program Editor Pulses Voice Report 18 To use this command simply select a voiced section of the sound then Editor Pulses Voice Report An information window will then pop up providing you with a variety of useful mea sures In addition to maximum and minimum pitch with additional statistics you will also be given the jitter shimmer harmonics to noise ratio HNR and the noise to harmonics ratios for the selected portion of the sound Jitter is a measure of the periodic deviation in the voice signal or the pitch perturbation of the signal Put differently each cycle of speech with a given Fp should in a perfect world have the same period The jitter
37. el and a known oral vowel to determine which peak is reinforced by the nasality You may need to examine several words before a clear winner emerges 3 Subtract PO from Al to get the measurement Because the nasal peak PO will be reinforced by the resonances in the nose during nasal vowel production nasal vowels will tend to have lower A1 PO values than non nasal vowels Across many tokens A1 PO can be a very good predictor of vowel nasality however there are several important things to keep in mind when using A1 PO to measure vowel nasality e A1 PO only works in situations where F is higher in frequency than H1 and H2 Most of the time this is true but for high vowels A1 and PO often occur at the same place in the spectrum leaving the measurement useless 3Many thanks to Dr Rebecca Scarborough on whose handout Measuring Nasality using A1 P0 this section is loosely based 26 Non nasal Vowel a ae mae 3 FREQ kHz b FIG 2 a The spectrum of an oral vowel is compared with b the spec trum of a nasalized vowel from the same speaker The spectral peaks that determine Al P1 and PO are labeled The amplitudes are measured by using the harmonic amplitudes closest to the expected peak according to theory Al P1 and Al PO are greater for the oral vowel than the nasal vowel 27 Figure 6 Figure 2 from Chen 1997 I showing A1 and PO in oral vs nasal vowels I
38. eristics of aperiodic sounds in speech release bursts and fricatives usually It is most often used to describe the production of fricatives with the understanding that sounds with a higher spectral COG are often produced more towards the front of the mouth and simply measures the overall weighting of the noise in the spectrum by reporting its center of gravity See Figure 7 for a more visual demonstration This measure can be useful in sociophonetic work as well as in fieldwork for determining the articulatory positions of different fricatives To measure spectral COG in Praat 1 Open the sound in an Editor window 2 Complete the steps in Section 6 9 to create a spectral slice in Praat at the point you d like to measure 3 Select the spectral slice in the Objects window then Objects Query Get Centre of Gravity 28 Sound pressure level dB Hz N i N e mm COG s Hii Mi W Ml vy i y i Sound pressure level dB Hz 20 204 Lower Spectral COG 0 0 i 205 104 0 2 i 104 Frequency Hz Frequency Hz Figure 7 Two spectra showing the higher spectral COG for a token of s here 8202 Hz compared with the lower spectral COG for a token of f here 3243 Hz An info window will then pop up presenting you with the spectral COG for the point repre sented by the spectrum For further information ab
39. etailed queries When working with other types of Praat objects e g spectra the editor window will allow you to query those objects as well When you make a query either in the editor window or from the objects window the Info Window will pop up with your results You can also print to this window when scripting in Praat see Section 11 Note that information printed here will not necessarily be saved and running a new query will overwrite it by default The Praat Picture window shown towards the end of the document in Figure is used to create and display publication quality images and is open by default when you start the program For detailed information about using the Pictures window and why it exists at all see Section 8 Sound help Draw X Query X Modify z C Annotate Analyse Periodicity m C Spectrum gt Formants amp LPC Y Points Y Manipulate To Manipulation To KlattGrid simple Synthesize Convert X Filter Y Combine 7 Figure 1 The Praat Objects Window Knowing the names of all these commands allow us to more easily describe the commands to use when working with Praat For instance if this guide says that you get the duration of a sound by using Objects Query Query Time Domain Get Total Duration that means roughly Go to the Objects window Choose Query then from that submenu choo
40. f discussion and URLs for various forced alignment tools in the intro to Section e 1 4 2 January 16 2014 Added Section 11 4 6 discussing nowarn noprogress and other ways to speed up your scripting on large datasets e 1 4 1 January 10 2014 Fixed a few typoes and updates based on Gareth Walker s feedback Thanks Gareth e 1 4 December 9 2013 Added discussion of the shift in command syntax in newer versions of Praat Section 11 3 3 Added discussion of units of intensity addressing the Pascal vs dB issues some of my students were having Section 6 7 1 Added further warning admonition doom and gloom to Section 6 12 about A1 PO as a measure of nasality which sadly is complicated Updated the Reasonably Recent Praat version number to encourage people to upgrade Added quick code example for finding odd and even numbers in a Praat script to Section 11 4 7 Added a brief discussion of while loops Section 11 4 3 e 1 3 6 October 2 2013 Added discussion of the smoothing of the intensity line and its relation to the pitch track in Praat e 1 3 5 March 22 2013 Updated License for the Manual A few typoes squashed 1 3 September 28th 2012 Added Section 7 7 Manipulating Duration with explana tions of how to slow and speed sound files 1 2 5 August 10th 2012 Added discussion of Praat Picture for more complex displays 1 2 May 19th 2012 A few small tweaks added a section on measuring Voice
41. f files Sometimes for perception experi ments and otherwise you ll find it necessary to filter your sound files Often sounds files will have extraneous background noise or in the case of particularly low frequency sensitive microphones room noise not blocked by sound attenuation In those cases you ll want to filter the sound file to remove it 7 4 1 Low pass filtering Low pass filters are useful for simulating high frequency hearing loss and cellular phone speech among other things They remove all signal above a given frequency To low pass filter a soundfile e g removing all sound above 2000 Hz 1 Load the sound into the objects window of Praat 2 Objects Filter Filter Pass Hann Band e From Frequency 0 e To Frequency 2000 or whatever yourd like your highest frequency sound to be e Smoothing 20 Hz 20 Hz is a good baseline This controls how soft the cutoff is 5 Hz is as low as you ll ever want to go for this setting 3 The filtered sound will be placed into your Objects window as Sound soundname_band 32 7 4 2 High pass filtering High pass filters are useful for removing low frequency noise from recordings which might seep through a sound booth They remove all signal below a given frequency To high pass filter a soundfile e g removing all sound below 2000 Hz 1 Load the sound into the objects window of Praat 2 Objects Filter Filter Stop Hann Band e From Frequency 0 e To Frequen
42. h the user interface or using Praat scripting 40 7 11 Synthesizing Sounds from scratch Praat offers the ability to synthesize sounds using a Klatt Synthesizer an articulatory synthe sizer the Vowel Editor and more The use of these synthesizers is outside the scope of this class but is well explained in the Praat Documentation 7 12 Source Filter Vowel Resynthesis When creating stimuli for vowel perception experiments as well as many other times it can be useful to generate vowels of a controlled quality Although Praat includes both articulatory and cascade Klatt synthesis as well as the vowel editor sometimes it s important to maintain the vocal characteristics of the recorded speaker In these situations you ll want to use Source Filter vowel resynthesis to alter the vowel s formant qualities without altering or replacing other significant aspects of the signal Source filter resynthesis is most efficiently done by script but can be done step by step by hand if needed To understand both the process and the workings of source filter resynthesis SFR it s impor tant to understand the source filter theory of vowel production This understanding of vowel production holds that a given vowel is composed of two element the source the voicing com ing from the larynx and the filter the articulations and anatomy of the vocal tract above the larynx When the source signal passes through the vocal tract the resonances in
43. hich pull down menu the command will appear in from the top of the window e Command specifies the text that will appear in the menu e After command and Depth pertain to the location of the new command in the menu Leaving the defaults will place the new command at the bottom of the menu Thanks once again to Dr Rebecca Scarborough from whose writing parts of this section are taken 56 e Script file should be filled in automatically if you are working from a saved Praat script To remove a script from a menu take the below step 1 Praat Menu Preferences Buttons 2 Choose the proper category Objects for scripts in the objects window menus Editors for scripts in the Editors window menus etc 3 Find the script you d like to remove 4 Click on ADDED such that it turns to REMOVED 5 Close that window and if needed restart Praat Editor scripts can also be associated with one of the Script Logs Log 3 or 4 in the Query menu of the Editor window To do this 1 Open a sound in the Editor window 2 Editor gt Query Log Settings 3 Type the path to the script in the Log Script 3 or 4 box Once this is completed you can use a keyboard shortcut to run your script Adding scripts to the Log Script slots is particularly useful for scripts which you might run extraordinarily often as you can then with some additional software set a button on a Multi button mouse to one of your log script keyst
44. ike spectral tilt it s a ratio measure of the ampli tudes of two harmonics A1 which is the highest harmonic peak near the first formant and PO which is a low frequency harmonic usually H1 or H2 which corresponds to a low resonance 25 in the nasal passages See Figure 6 for an illustration of these peaks in spectra To compute A1 PO you need to take three main steps 1 Find Al and measure its amplitude Al is the highest harmonic near the frequency of the first formant F can be located as described in Section 6 6 The frequency of F will vary from vowel to vowel tending to be lower for high vowels and higher for low vowels The amplitude of Al though will not vary by vowel quality 2 Find PO and measure its amplitude PO is a specific harmonic peak which is reinforced by resonances within the nasal passages The frequency of PO will be specific to each speaker and won t change from word to word as the speaker s nasal passages are unlikely to change resonant character istics or from vowel to vowel The amplitude of PO will change from word to word depending on the degree of openness of the velopharyngeal port Although each talker is different PO is likely to correspond to either H1 or H2 fora given speaker In general for speakers with lower pitched voices PO will be H2 and for speakers with higher pitched voices PO will likely be H1 The best way to identify this peak is by examining a known nasal vow
45. ing can t find voicing To help prevent these failures which will crash the entire run of a script you may considering adding a small block of code like the following which will only take a certain action if the answer is defined if pulse_begin_time lt gt undefined Get pitch endif Once again comment your code If I had a nickel for every time ve opened up a script I wrote only to find myself unable to understand what I had written Pd have a lot more nickels A great many issues in Praat scripting can be resolved by looking at a timepoint just 5 10 ms to either direction Adding in a loop which if an unreasonable measure or an undefined is encountered tries again at a nearby second timepoint can really increase the robustness of your scripting If your script is automatically creating lots of objects you ll want to clean house peri odically Although it s ideal to hard code the deletion of every item manually select Sound sounda Remove sometimes you wind up generating a large number of no longer needed files A little chunk of code along the lines of the below will do the trick nicely select all minus Sound soundnames minus TextGrid soundnames minus whatever other files you care about Remove e To check if a number is even or odd in a Praat script use the mod command oddness number mod 2 if oddness 0 elsif oddness 1 endif print Number is even print
46. ipt will look like Spectrogram settings 0 5000 0 025 50 That s it Because this code works entirely with the Editor window you ll want to open it as an Edi tor script You can use the Editor File Open Editor Script command to open it and run it from there or you can add it to a menu likely Spectrum using the procedure in Sec tion 11 2 2 Once you ve done that if you want to change the spectrogram type you re only a click away You ll likely end up with a few of these scripts in that menu to change the spectrogram into 62 broadband narrowband 0 10000 Hz broadband and so forth But sometimes you need to get a bit more complicated 11 3 6 Scripts with Variables Variables are constructs in programming which are just labels which store pieces of information either numeric or string text In Praat they have a few characteristics worth noting e Variable names have to start with a lower case letter so as not to be interpreted as commands to the program and must not contain spaces or start with a punctuation mark e String variables containing text must end in the character e The sign is used to assign values to variables e g fO 120 stores 120 in the variable f0 e Values for string variables must be placed in double quotes So to specify a file s name soundname fifteen_minutes_suzanne For a more concrete demonstration let s take another task In Acoustic and Au
47. ke a formant listing for 3 formants e For pitch include the single quotes time 4 tab f0 2 This will give you the time time and fundamental frequency Fo at the cursor point like a pitch listing c Close the Log Settings window 3 You can now go back to the editor window and record duration formant frequencies or Fo by simply selecting the relevant point or selection in the waveform or spectrogram and hitting F42 for log 1 or Shift F 2 for log 2 7Large parts of this section are taken from a handout by Dr Rebecca Scarborough for a previous LSA institute All credit belongs to her 51 e By default each measurement will display in an Info window as well as write to the file you set up If you want you can log to the log file or the Info window only by changing the settings for Write log 1 to or Write log 2 to in the Editor Query gt Log Settings window 4 You can modify logs to include any compatible bits of information using the following variables e time Time at cursor or at midpoint of the current selection e tland t2 Time at beginning and end of selection e dur Duration of selection e fO Fo at cursor or average Fy of selection e f1 f5 Formant at cursor or average for selection e b1 b5 Formant bandwidth at cursor or average for selection e intensity Intensity at cursor or average for selection e tab tab 11 Scripting in Praat 11 1 What is Praat scripting
48. ke a spectral slice you ll need to do the following 1 Editor Spectrum Spectrogram Settings Set Window Length to 0 025 effectively producing a narrow band spectrogram Editor Spectrum Advanced Spectrogram Settings Set Window Shape to hamming no A 0 N Select the point at which you d like to see the slice taken 6 Editor Spectrum View Spectral Slice This will create a new Spectrum object and pull up a window like that in figure 5 showing amplitude on the Y axis and frequency from 0 up to the Nyquist frequency on the X axis You can zoom in and out using the buttons in the bottom left corner as you wish If you ve selected a portion of the sound rather than a single timepoint when you use Edi tor Spectrum View Spectral Slice Praat will create a spectrum representing the average characteristics across the entire selection which isn t useful for most of the spectral measures discussed below 6 10 Measuring Harmonic Amplitude Frequency Getting harmonic frequency and amplitude in a Spectrum Editor window is fairly straightfor ward as clicking anywhere within the spectrum editor window will give you the frequency and amplitude measurements at the cursor So to find the amplitude and frequency of a given point in the spectrum click that point and read off the amplitude on the left and the frequency at the top as shown in figure 5 This can be done even more easily and efficient
49. lipping in your file which is a Bad Thing One 71 or two samples may be fine but in a production script you ll want to Scale Amplitude or Scale Peaks to make that stop If you re doing the same process over and over again in a highly automated fashion on a fast machine you ll notice that Praat spends more time rendering the Progress To Pitch type of dialogs than it does making the pitch file To suppress the generation of these dialogs letting Praat run more silently in the background use the noprogress directive select Sound soundname _mod noprogress To Formant burg 0 formnum formrange 0 0256 50 noprogress To Pitch 0 60 crazyhighhl1 This will generate the formant and pitch objects without displaying a dialog allowing the process to run much more quickly than it otherwise would have This will have the side effect of effectively preventing the user from stopping the script mid run without force quitting Praat but the gain in speed may offset this inconvenience Finally it s important to realize that as you re scripting anything that actually displays on the screen will be more resource intensive than a background task especially if a spectrogram is being generated As such if you have the choice of doing a given process using the editor window Open Sound in Editor Move cursor to point X Get First Formant Get Second formant close editor window or creating and querying an object To For
50. llation will vary depending on your platform e MacOSX Just drag Praat into your Applications folder e Windows XP Vista 7 Download the installer and run it and a link to the program will be placed on your desktop e Linux If you re running Linux you ll be able to figure out the install on your own Many distributions have Praat as an installable package in their repositories but check the version numbers as you won t want anything older than 5 2 x 3 About Praat 3 1 Praat Windows Once you ve opened Praat a variety of windows will open automatically and there are many other windows which will pop up when using the software It s best to discuss these now so we can refer to them by name later when discussing the path to certain commands The Praat Objects window Figure 1 is where you ll start most workflows using this menu to open create and save files as well as to open the various editors and queries which you ll need to work with sound files The Editor window Figure 2 is where you ll spend most of your time and can be accessed by selecting a sound and choosing View amp Edit When examining a sound file the editor window will show the sound s waveform on the top and a spectrogram on the bottom and the cursor will allow you to take selections and measurements The menus along the top will allow you to show and hide different bits of information formants pitch intensity as well as to make more d
51. ly by script allowing you to find the highest point on a given harmonic without clicking guesswork 24 6 11 ANO 3 Spectrum FFT_922ms File_ Edit Query View Select Help 1608 43 42 1 dB 1608 43 3391 57 o Window 5000 00 Hertz 5000 00 17050 00 Total bandwidth 22050 00 Hertz al Cin Cour Gel Coalo E lt gt OGroup Figure 5 A spectral slice Editor window Measuring Creakiness and Breathiness using Spectral Tilt Spectral tilt is often used in phonetic research as a measure of creak As discussed in Gordon and Ladefoged 2001 3 One of the major acoustic parameters that reliably differentiates phonation types in many languages is spectral tilt i e the degree to which intensity drops off as frequency increases Spectral tilt can be quantified by comparing the amplitude of the fundamen tal to that of higher frequency harmonics e g the second harmonic the harmonic closest to the first formant or the harmonic closest to the second formant Spectral tilt is characteristically most steeply positive for creaky vowels and most steeply nega tive for breathy vowels Spectral tilt is easily measured by finding H1 and H2 measuring their amplitudes as described above and comparing the two numbers 6 12 Measuring Nasality using A1 PO A1 P0 is an acoustical measure of nasality first described by Marilyn Chen in Acoustic correlates of English and French nasalized vowels 1 L
52. lysis and manipulation 5 Opening and Saving Files 5 1 Opening Files If you already have a sound file recorded that you d like to open recorded in aiff wav or flac format there are two ways to open it in Praat If you re using Praat on OS X you can drag supported files onto the Praat icon in the dock However if that doesn t work or if you re on a different platform Objects Open Read from File Then use the next dialog to find the files you re interested in on your hard disk Once you ve loaded the files they ll appear in your objects window for further use Note that other files created by Praat can be opened in the same way Tip Praat can t open wma mp3 or m4a audio files To convert these easily to wav files en masse download iTunes set it to import files in wav or aiff format in Preferences and use iTunes Advanced Create wav version 5 1 1 Working with longer sound files Praat has historically had trouble working on sound files more than 20 minutes long and if you re using a 32 bit version or have little available memory you may experience frequent out of memory errors working with large files unless you use the Objects gt Open Open long sound file option However sounds read in as Long Sound objects cannot be used for all measurements It s recommended to cut your files into chunks shorter than an hour either using Audacity or by editing the Long Sound object as described
53. mant Get Value at time 1 timepoint Get Value at time 2 timepoint it will certainly be faster to use an object and leave the editor closed Editor scripting is great especially as you re just starting off but if you re planning to run on a large number of items removing Editor Scripting from the mix will almost certainly result in a speed increase over huge datasets 11 4 7 Useful tips These are a few tips and tricks that I learned well after they would ve saved me hours upon hours of time I m passing them along in hopes that they ll save you the time more quickly e To refer to an object in the Objects window it s best to give both its type Sound TextGrid etc and its name So instead of coding select sounda you ll want to use select Sound sounda e If your code is failing sometimes the line numbers in the crash messages won t tell you exactly how far the script is getting before it crashes To test this insert the word fail or anything else that isn t a real command into your script at a certain point The moment it hits that word the script will crash and you ll know you ve gotten that far Then repeat 72 until you crash for some other reason At that point you ll know exactly where your script goes off the rails Scripts will sometimes fail talking about a certain variable being undefined This usually means that you re looking for a pitch or pulse in a place where Praat s pitch track
54. n the editor window So here three steps of measurement and calculation are condensed into one easy ment selection 64 11 4 About the Praat Scripting Language We ve already talked about variables but there are several other programming constructs used in Praat scripting which you ll need to know about to successfully script 11 4 1 for loops In Praat sometimes you ll want to do the same thing over and over again for e g each item on a list or for each vowel in a TextGrid To do this you ll use a for loop For loops iterate through large amounts of data doing the same thing many times over and over again for loops have the form for variable from 1 to another variable Take this action for each of them endfor In Praat for loops usually have the format for var from 1 to other var followed by an indented block ended with an endfor to tell Praat when to stop Here s a sample script select TextGrid sounda number_intervals Get number of intervals 2 for k from 1 to number_intervals Set interval text 2 k Vowel endfor This script selects a TextGrid named sounda gets the number of intervals in the TextGrid then goes through and changes the text for each interval in tier two of that TextGrid to Vowel Really though the best way to understand for loops is to see them in action and to look through other scripts It s worth noting that if you always plan to start from the fi
55. n speaker 6 6 2 Improving Formant Finding results For most speakers the default settings will suffice but if you find Praat to be struggling with missing or the addition of extra formants you ll likely find that that particular speaker s for mants are more effectively measured if you make some tweaks to Praat s Formant Settings helping the computer with its task To apply any of these changes you ll want to open the Formant Settings window see Fig ure 4 Editor Formants Formant Settings Praat has to make a series of guesses about how many formants it will find and how spread out those formants will be We typically will assume that speakers will have one formant per 1000 Hz and thus that there will be 5 formants in the 5000 Hz we usually worry about for 20 speech research Thus 5 is the default setting for Number of Formants and the highest we ll look for formants the Maximum Formant is 5000 Hz by default Usually you ll only need to adjust the Number of Formants Although 5 formants is a good baseline if Praat is finding formants where there are none between two actual formants usually you should lower this value down to 4 or 3 If Praat is finding too few formants missing F and labeling F as F for instance you ll want to raise this number up to 6 If you re working with a child a person of unusually small stature or somebody with an oth erwise tiny vocal tract you may find that the Praa
56. n these situations A1 P1 a second nasal resonance peak 950 Hz described in I is a better measure of vowel nasality e A low Al1 PO relative to known oral tokens is a good predictor of nasality across a large number of tokens but individual nasal oral vowel pairs may or may not demonstrate a strong effect It should not be used to measure the nasality of one individual token compared to another e A1 PO should only be examined in comparison with other tokens An A1 PO of 2 may be normal for an oral vowel for some speakers but indicate extreme nasality for others The absolute value of A1 PO is not easily interpretable across speakers e Remember here you re relying on Praat to give an accurate measurement of the first for mant Feel free to tweak the formant settings and don t blindly trust Praat s formant tracker to find what linguists call the first formant and not some other spectral promi nence This is a complex measure and I personally have spent a great deal of time working with it and its measurements Although it alongside A1 P1 is the best acoustical approach to nasality presently available it is also remarkably noisy capricious and complex A1 PO nasality should be one element of your successful analysis not the sole element and as I have discovered no nasality experiment is simple 6 13 Measuring Spectral Center of Gravity Spectral center of gravity Spectral COG is useful for measuring the frequency charact
57. ne numbers where your script crashed and it s less of a pain to just scroll than to use Script Editor Search Go to line and the sorts of advanced find replace tools present in more robust editors Some good editor choices include For Mac OS X e TextMate 2 Version 2 is free and open source http macromates com e MacVim https code google com p macvim e SublimeText http www sublimetext com For Windows e Notepad http notepad plus plus org also Scott Sadowsky s Notepad Syntax Highlighting package for Praat at http sadowsky cl praat htmlitsyntax e TextPad http www textpad com e SublimeText http www sublimetext com For Linux e Kate http notepad plus plus org See Jos Joaquin Atria s Kate syntax high lighting package for Praat at https github com jjatria praatKateSyntax e SublimeText http www sublimetext com 58 11 3 2 Filenames Praat has a few odd quirks involving filenames which you ll need to work around in your script ing First Praat chokes on filenames with decimals in them Be careful Also absolute file paths in Praat scripts will need to be referred to differently on Windows machines vs on Macs e directory c Documents test data Windows e directory Users will Documents test data Mac On Unix like systems can be used to refer to the home directory Users will Relative file path names relative to where
58. ngs 2 Set the Window Length to 0 025 or the narrowband window length of your choosing 3 Click OK Now harmonics should clearly be visible in the spectrogram To return to a broadband spec trogram 1 Editor Spectrum Spectrogram Settings 2 Set the Window Length to 0 005 or the broadband window length of your choosing 3 Click OK And you ll be back to the default broadband spectrogram 6 3 Measuring Duration As you might expect measuring duration is quite easy Once the sound file is open in the Editor window 1 Select the portion of the file you d like to measure e g the vowel with the cursor 2 Read the duration of the selection in seconds from the duration bar along the bottom of the Editor window OR 3 Editor Query Get selection length and read your selection in the info window If yow d like the duration of an entire file just select the file in the Objects window and Objects Query Query Time Domain Get Total Duration 6 3 1 Measuring Voice Onset Time VOT Voice Onset Time VOT is the time between when the stop is released and when the voicing of the following vowel begins Measuring this time which can be positive say for the En glish voiceless aspirated stop t a around zero for the English voiced stop d or more commonly the voiceless unaspirated ta around the the world or negative for fully voiced 14 stops where voicing starts before the stop is released a
59. nipulate the speaker s pitch in already recorded sound files To create a manipulation object which allows you to change a sound s pitch and duration 1 Load the sound into the objects window of Praat 2 Objects To Manipulation e Leave Time Step unchanged e Set the pitch range to 75 600 Hz 3 Select the newly created Manipulation Soundname then Objects View amp Edit This will open a manipulation window like the one shown in Figure 8 It shows you the pitch track in the center as well as the waveform The blue lines on top of the waveform represent pulses This window allows you to modify the duration and pitch of the sound by creating and moving pitch points A good first step is stylizing the pitch contour which will change the detailed contour into something more manageable Manipulation Pitch Stylize Pitch If you still have too many points select a few by selecting a part of the sound and go to Manipulation Pitch Remove pitch point s If you need a different pitch point place your cursor where you want a point and Manipulation Pitch Add pitch point at cursor You can now drag the individual green pitch points around to raise and lower the speaker s pitch at different points throughout the word to great phonetic and comedic effect To save the result of your manipulations use Manipulation File Publish Resynthesis and a pitch modified copy of the sound will be placed in the
60. out Spectral Center of Gravity and an example of its use in fricative description and cross linguistic comparison showing the relationship between articulation and spectral COG refer to Gordon et al 2002 A cross linguistic acoustic study of voiceless fricatives For an example of this measure used in discussing gender differences in spectral COG refer to Jane Stuart Smith s Empirical evidence for gendered speech production s in Glaswegian 141 7 Creating and manipulating sound Files in Praat 7 1 Creating sounds from Formula To create a sound from formula a pure or complex tone you ll want to use Objects gt New Sound Create sound from formula There you can plug in a formula which will generate the sound you want For instance To create a 1000 Hz puretone at 0 5 dB 1 Objects New Sound Create sound from formula Paul Boersma has stated in correspondence that this paper incorrectly implements Spectral COG leading to inconsistent results and thus should not be emulated For more information see Boersma amp Hamann 2008 from http www fon hum uva nl paul papers BoersmaHamannPhonology2008 pdf Footnote 7 29 e Under formula enter 1 2 sin 2 pix 1000xx e Specify the time sampling frequency number of channels and such as you desire To create a 250 Hz puretone at 1 dB 1 Objects New Sound Create sound from formula e Under formula enter 1 sin 2 pix250 x e Specif
61. pecifying on the following line which tiers if any are point tiers Tiers will be ordered in the order named 4 Select both the sound you d like to annotate and the associated TextGrid and click Objects View amp Edit Once your TextGrid is created you ll be presented with the TextGrid Editor Window Figure 13 To annotate the file Click on the tier you d like to make an interval on Using your mouse select the part of the word you d like the interval to contain Hit the lt Return gt key Click on the interval you ve just created and name itf Repeat for other intervals on the same tier as well as any other tiers Ou 91 oP INES Points are created by clicking on a point tier placing the cursor where you d like the point and hitting lt Return gt gt Although the window which is opened when a sound and TextGrid are both selected and View amp Edited looks a lot like the Editor window Praat considers it to be a very different sort of window Any scripts added to the Editor window see Section TT will have to be added separately to the TextGrid editor window and some menu options present in the Editor window are not present in the TextGrid editor window SYou can use IPA characters in TextGrid labels provided you have the proper Unicode IPA fonts installed but when exporting the labels by script or elsewhere all programs used for analysis must be Unicode aware Most modern programs are but many command line p
62. r window s formant track It often happens that if one of the measurement tactics misses or adds a formant the other will not so a measure where both are in agreement is often more trustworthy than one where they disagree significantly The author cannot explain the discrepancy but is quite happy to leverage it extensively in his scripting 6 7 Measuring Intensity Amplitude Measuring intensity in Praat is relatively straightforward albeit with a major disclaimer To get the overall intensity of a sound select the desired sound and run Objects Query Get Intensity dB To get the intensity at a specific point in the sound open it in an editor window Editor Intensity Show Intensity and then use the various commands available in the Editor Intensity menu to get whatever information you desire By default Praat s display of the intensity of a word is smoothed to avoid showing individual pulses in the amplitude lines both in the editor window and in amplitude objects when drawn or viewed This smoothing is based on the minimum FO of the sound If you want to see something closer the amplitude envelope of the sound in Praat where pulses show up individually as amplitude peaks or if you want the amplitude curve to be smoother than it normally would be you must simply adjust the minimum pitch expected by Praat This can be done in Editor Pitch Pitch Settings as described more fully in Section Similar smoo
63. rm of the sound and if the sound is sufficiently short a broadband spectrogram showing the spectral energy of the sound over time In addition you might also be presented with a series of red dots representing formants blue lines representing the speaker s pitch and a yellow line representing intensity These can be enabled and disabled in the Editor View Show Analyses menu Clicking within this window will place the cursor on the waveform and spectrogram If you click within the editor window the cursor will spawn two dotted lines A vertical bar shows the time within the sound where you clicked labeled at the top in seconds and if you clicked within the spectrogram a horizontal bar shows the frequency at the cursor labeled on the left in red If the pitch or intensity tracks are displayed where the cursor is placed values at the time the cursor represents are given on the left side of the editor window 11 In addition you can click and drag or use the Select menu to select portions of the sound The time of the start and finish of the selection will be displayed in red and the duration of the selection in seconds will be displayed in the top of the bar To play a sound in the editor window use the three gray bars at the bottom of the editor window The bottom most bar Total Duration will play the entire sound The middle bar Visible Part will play only the visible portion of the sound The different sections of
64. rograms such as SPSS or Python are not so if you re planning to use any non Unicode aware programs you re best served using SAMPA or some other means of transliterating IPA characters into ASCII text 48 File Edit Query View Selec Interval Boundary Tier Spectrum Pitch Intensity Formant Pulses til ih i STN AMAL ATA NOAA edil titi las adi ded a ds Figure 13 The Praat TextGrid Editor Window Once your file has been TextGridded as above looking something like Figure 14 you ll want to save the TextGrid file either from the Objects window Objects gt Save Save as Text File or within the TextGrid editor TextGrid Editor File Save TextGrid as Text File TextGridded files can then be read in by Praat scripts which measure only certain parts of the word can be split and labeled according to a given tier by script see the file_segmenter praat script or can simply be examined with the benefit of the labels Once all your files have been TextGridded you ll be in a much better position to start automatically measuring data and manipulating your sound files 10 Using Log Files So far all discussion of measurement has assumed you would be taking individual hand mea surements and writing them down on your own These last two sections describe two ways to more efficiently capture data from your measurements Praat has the ability to easily capture the measurements you take as you mov
65. rokes For instance if you have a script that will take the current selection create two TextGrid boundaries label it vowel then resize the view to the next interval on another tier you could Bonus bind it to a log script then just make a selection click a mouse button rinse and repeat saving countless hours 11 3 Creating a new script At its core a Praat script is just a plaintext file with commands meant to be read by Praat As such creating a script is as easy as saving a text file then editing the contents The easiest way to do this is using Praat s built in Script Editor To create a new Praat script Thanks to Kathleen Currie Hall for pointing this out during the LSA Praat workshop 57 1 Praat Menu New Praat Script 2 Script Editor File Save e Save it wherever you d like on your machine and use praat as an extension not because it s required but because it can t hurt will help you remember what the file is and allows Praat to open the file as a script if dragged onto the Praat icon 3 Begin writing saving often 11 3 1 Using other text editors Although Praat has an editor built in which is quite capable praat scripts can be created from within any plaintext editor Using an external editor allows you features like syntax highlighting Praat script is similar to Perl in enough ways to make Perl syntax highlights vaguely useful always on line numbers because Praat gives you li
66. rsor at a given point in the file and Editor Pitch Get Pitch Running Editor Pitch Get Pitch when a chunk of the sound is collected will return the average pitch during that selection 6 4 4 Improving Pitch tracking by changing the Pitch Settings It s worth noting though that Praat s pitch tracking can be quite finicky You will often see it jump up and down doubling and halving the actual Fo and in many cases especially where the speaker is at all creaky the pitch track will drop out altogether This does not represent any specific failing of the software but instead comes from the variability and noise inherent in actual phonetic data Part of the strength of Praat s approach is that you as a user can help Praat improve its pitch tracking for a given file or speaker by changing some of the Pitch settings So in order to do any serious research using the pitch track and to avoid some of the problems discussed above you may need to adjust some of the pitch settings to help Praat s pitch tracker better reflect the speaker s voice To do so Editor Pitch Pitch Settings Then adjust the settings as follows e Pitch Range Hz 16 Set the pitch range to a reasonable range 50 400 for general usage going much higher for song or children s voices If you have a good idea what the speaker s ac tual range is taken from a narrowband spectrogram for instance set the minimum to just under th
67. rst iteration you can leave off the from 1 from the statement So the above could be written as select TextGrid sounda number_intervals Get number of intervals 2 for k to number_intervals Set interval text 2 k Vowel endfor and it would function identically 65 11 4 2 if statements if statements tell Praat to take a certain set of actions only if the requested conditions are met This condition is usually checking whether a variable is equal to or greater lesser than a certain value but it can get more complicated than that if statements have the form if variable something Take this action endif Here are a few example if statements that you might see in a script vowel_label Get label of interval 1 2 if vowel_label i Set interval text 2 2 HighFrontVowel endif The above code will change the TextGrid s label to HighFrontVowel only if the vowel s label Way is i vowel_label Get label of interval 1 2 if vowel_label i Set interval text 2 2 AnotherVowel endif The above code will change the TextGrid s label to AnotherVowel only if the vowel s label is 579 not i As you can see if statements are incredibly useful and will show up constantly to control the flow of your scripts You ll learn to love them very quickly You can also use else and elsif to allow yourself multiple choices vowel_label Get label of interval 1 2
68. s One small but worthwhile note is that Praat actually draws a division between scripts and editor scripts They use the same syntax the same commands and are stored in the same way but some scripts are meant to run within the Editor window because they use the functions in that window and some are meant to run from the Objects window Simply put if there s a script whose function is only useful once you ve already opened the sound you care about in the editor window it s going to be run as an Editor script but if a script needs access to more than one sound or to the functions in the Objects window it ll run from the main windows There is some flexibility here though as you can always use the Edit and Editor commands to work within the editor in a Praat script and using endeditor can bring you back to the Objects window from an editor script The primary way in which this distinction matters is that you ll open Editor scripts using the Editor File Open Editor Script option whereas you ll open regular Praat scripts with 54 Praat Menu Open Praat Script Sometimes you ll download a script from the internet or from a friend and it just won t run or it ll fail in odd ways In those situations try running it as an Editor os script or as a Praat script if you re trying it in the Editor This is a simple step that if it works can save you hours of frustration and troubleshooting as there s often no D
69. s is also a situation where using a good Praat script can speed things up significantly and allow the rapid repetition of small changes to improve output Given some work though and some time this can be an excellent way to modify vowel quali ties For examples of this in use for stimulus preparation contact the presenter or examine the 42 author s Establishing the Nature of Context in Speaker Vowel Space Normalization 5 8 Exporting images for use and publication To be completely honest the fastest and usually sufficient means of getting images from Praat for documents or presentation is arranging the windows to display what you d like and then taking a screenshot which can later be cropped However with a bit more work Praat can be used to create and annotate publication quality graphs The Praat Picture window Figure 10 is used to create and display images Using the Praat picture window can be thought of as a five step process Create an object choose your size draw your object into the picture window garnish and export To give a brief example let s say you d like to export a spectrogram of sounda 1 Select sounda Objects Spectrum To Spectrogram e Set the Spectrogram settings using the same settings you would in the Editor win dow see Section 6 2 2 Click and drag in the picture window to set the size youd like e Realize that these images scale nicely so the default usually suffices
70. s found in most non English languages Languages classify their stops largely based on Voice Onset Time and it s an excellent more gradient empirical measure of the voiced voiceless phonological distinction Measuring Voice Onset Time VOT is very easy to do in Praat as it s just a duration measure ment between two set points the release of the stop and the start of voicing 1 Find the stop release Find the start of voicing Select the span between these two points gt UN Read the duration of the selection in seconds from the duration bar along the bottom of the Editor window OR i Editor Query Get selection length and read your selection in the info window 6 If the start of voicing came before the stop release the VOT is negative Otherwise the VOT is positive In general voiced sounds in languages other than English will have a VOT which is negative voiceless unaspirated sounds will have a VOT which is around 0 and aspirated sounds will have a positive VOT 6 4 Examining and measuring F Pitch Fo and Pitch can be measured in a number of ways in Praat more and less reliably 6 4 1 Measuring Fo from a single cycle The surest way to get an accurate Fp for a single cycle is to open the file in the Editor window then 1 Zoom in to the point where you can see individual cycles in the sound file 2 Select one complete cycle as accurately as possible thus giving Praat the period in seconds
71. s months years later Here s an example of some commented code Remember Praat will only see the lines which don t start with Now this next chunk starts a for loop that just goes through the above directory and keeps reading in files each time it iterates for j from 1 to number_files select Strings list filename Get string Read from file directory filename At this point we now have the variable soundname which refers to the file being worked on soundname selected Sound 11 4 6 Scaling scripts up nowarn noprogress and avoiding the editor window Lengthy praat scripts meant to run on a great many sounds in a highly automated way benefit greatly in terms of speed and efficiency by reducing the number of dialogs which pop up If you re doing something which modifies a sound in a way that occasionally produces a tiny bit of clipping yielding an error message like Advice 2 of 34583 samples are clipped upon saving you can use the nowarn directive to save without warning For instance select Sound soundname _mod nowarn Write to WAV file directory output soundname _modified wav select TextGrid soundnames Write to text file directory output soundname _modified TextGrid This will save the file as a wav file and completely ignore any errors resulting from clipping Mind you this means that there will be some c
72. s present in Praat nor cover all of the quirks of the package but this workshop will hopefully leave you feeling more at home in Praat and give you an opportunity to go forth and explore further on your own 2 1 Versions This guide will assume that you are using a relatively recent build of Praat 5 3 60 and there s no reason not to download the latest version whenever released All screenshots will be from Praat 5 3 60 running on Mac OS X but your copy on your platform should not differ sig nificantly Unless otherwise specified workflows for making measurements and manipulations do not differ significantly across platforms 2 2 Other Resources Although this guide aims to be painfully comprehensive there are many other resources avail able for helping with Praat The first step for dealing with any issue is Praat s built in help guide accessible from the upper right corner of most windows in the program You ll be best served by starting with Intro and moving from there There are also a variety of tutorials for Praat available online and the Yahoo Groups Praat users group whose archives can be searched at the below link http uk groups yahoo com group praat users You will want to search the archives before posting as there are likely a great many people who have had your question before in the history of the software 2 3 Getting and Installing Praat Praat can be downloaded fromhttp ww praat org and its insta
73. s the amplitude Get intensity dB Renames it Rename My_awesome_sound Prints a message into the Praat information window print Script Finished Note though that Praat scripting isn t the same as writing a new computer program Praat scripting uses the same commands as you use in the GUI and only works within Praat whereas coding say in C is much more opaque but programs in C can be compiled to run on many different devices and don t need specific programs That said there are a few things that Praat scripting cannot do 1 Praat scripts can t label your data or recognize speech e Praat doesn t know what s being said so you need to TextGrid annotate your files such that Praat knows where to look for the vowel s or consonant s that you re interested inf 2 Praat scripts only run in Praat although the system command can control the OS and some other programs e Praat scripting only affects Praat so you can t incorporate a step which say opens another program to run it 3 Praat scripts can t generate measurements as consistent as hand measurements e Individual words can be odd Humans can make small adjustments taking the pitch measurement just to the right of that bit of creak but Praat doesn t know enough to do that 8This can sometimes be accomplished in a more automatic albeit error prone way using Forced Alignment programs like FAVE align http fave ling upenn edu usingFAAValign h
74. se Query Time Domain then Get Total Duration 4 Recording Sounds To record sound using Praat you ll want to plug in your microphone sound card or external ADC Analog Digital Conversion box to your computer before starting Praat and then Objects gt New Record Mono This will pull up a recording menu which allows you to choose a sampling frequency the default 44100 Hz is fine for most purposes a microphone or other sound source and whether to record amono or stereo sound Press Record to record and Stop to stop being careful that the sound level bar stays within the green range to avoid clipping Once you ve made a recording name it and choose Save to list and it will now show up in the Praat objects window where it s ready for editing If you don t see a green bar indicating that Praat hears you while you are recording try changing the Input source on the left side of the SoundRecorder window If this doesn t help go to the computer s sound control panel to ensure the proper microphone is selected and that the input volume is not turned way down Praat only records in one minute long chunks out of the box To record longer sounds you can either change the buffer size in Praat Preferences Sound Recording Preferences or you can use Audacity free available from http audacity sourceforge net to record the session and then import the sounds into Praat see Section 5 afterwards for ana
75. st done using overlap add resynthesis Objects Window Get Resynthesis overlap add 7 8 Matching Intensity It s useful especially when splicing or sound combination is occurring to be able to ensure that two sounds are of the same overall intensity This is not extremely accurate and for precise perception studies there are more complex methods but for most purposes this will produce a good amplitude match To scale Sound A to the same average intensity as Sound B 1 Load both Sound A and Sound B into the objects window of Praat 2 Select Sound B Objects Query Get intensity dB e Make note of this number it s the average intensity of B 3 Select Sound A Objects Modify Scale intensity e Fill in the value obtained in step 2 for New Average Intensity dB 4 Sound A will be modified in place overwriting the prior unmatched version and can then be saved 7 9 Combining Sounds There are two ways to combine two sounds using Praat The first will sometimes work well and works best when both sounds are to be added equally and have the exact same file length To combine overlay Sound A and Sound B 1 Load both Sound A and Sound B into the objects window of Praat 2 Select Sound A and Sound B together 37 3 Objects gt Combine Combine to Stereo e This will create a new sound which has Sound A in one track and Sound B in the other 4 Select the sound created by the last step 5 Objec
76. t you can add the script as a button on the right hand side of the Object window called a dynamic menu This will only work for Non Editor scripts To do this 1 Open the Script such that it s available in a Script Editor window 2 Script Editor File Add to dynamic menu 3 Fill in the settings as below in the Add to dynamic menu dialog box e Class and Number refer to which object types and how many must be selected for the new script button to appear For example if you had a script that required a sound and a text grid you would put Class 1 Sound Number 1 1 Class 2 TextGrid Number 2 1 You would leave Class 3 blank e Command specifies the text that you want to appear on the button e After command and Depth pertain to the placement of the button If you leave them blank the button will appear at the bottom of the dynamic menu e Script file should be filled in automatically if you are working from a saved Praat script The other option is to add your script to a pull down menu in the Object window You can follow the same directions to add an Editor script to an Editor window menu To do this 1 Open the Script such that it s available in a Script Editor window 2 Script Editor File Add to fixed menu 3 Fill in the settings as below in the Add to fixed menu dialog box e Window specifies whether the command will appear in an Object window menu or a Picture window menu e Menu specifies w
77. t is finding non existent formants between the speaker s F and F and missing the speaker s higher formants F3 and F3 altogether In this situation you d want to increase the Maximum Formant Hz value to tell Praat to search a bit higher up in the spectrum for formants and perhaps lower the number of formants it s searching for Realize though that Praat can always find more peaks and there are often small peaks not perceptible to humans which may still have an acoustical relevance When there are too many formants Praat is not necessarily finding formants which aren t there but is finding addi tional peaks which although present aren t the F F and F peaks which we as linguists are chiefly interested in When there are too few Praat is just giving you only the most promi nent peaks that you ve asked for The results of Praat s formant tracker in reality are largely determined by what you re asking it to find and this settings adjustment be done with a mind to what you re actually interested in Dot size mm simply controls how large the red dots in the formant display are Although changing this can be useful if the track obscures the spectrogram this will have no effect on your measurements Just remember these settings persist even once you ve closed Praat so if you make adjustments here you ll want to return these settings to the defaults when you ve finished with your odd speaker No matter your set
78. t the vowel formants are Editor Formants Show Formants This will overlay a series of red dots onto the image which represent peaks in the series of LPCs which Praat has run This formant track can be queried at any time in a variety of ways all accessed through the Editor Formants menu If you re interested in a single formant s height you can place the cursor where you want a measurement and choose Editor Formants Get formant but it s 19 ANOO Formant settings Maximum formant Hz 5300 0 Window length s 0 0256 Dynamic range dB 30 0 Dot size mm 1 0 all of your advanced settings have their standard values your time step strategy has its standard value automatic Help Standards Cancel Apply OK Figure 4 Praat s Formant Settings Window often more efficient to use Editor gt Formants gt Formant Listing which will give you heights for F Fo F and Fy along with the timepoint at which the measures were taken In addition if you re interested in formant bandwidth bandwidth for the first four formants can be taken using the Editor Formants Get Bandwidth commands For hand measurement using Editor Formants Formant Listing and sanity checking by visually inspecting the formants on the Spectrogram will usually produce reasonable results but there are ways to improve Praat s formant picking performance for a give
79. the mouth heighten some frequencies and damp others In this way a relatively unremarkable voicing spectrum passed through a vocal tract with an i tongue shape ends up with formants at 250 Hz 2500 Hz and 3000 Hz your resonance may vary Source filter resynthesis takes advantage of this idea to modify vowel qualities by taking the following steps in the abstract 1 Take a recorded vowel and locate the overall peaks and valleys in the spectrum the formants by using an LPC linear predictive coding algorithm e These peaks and valleys at least theoretically should represent the resonances in the mouth caused by a given tongue shape 2 Use this information to reconstruct the voicing signal the source without those peaks and valleys e This is accomplished by inverse filtering the signal with the LPC raising the parts of the spectrum which the LPC says are low and lowering the parts which the LPC says are high The end result ideally will be the source signal as if the person had no vocal tract at all 41 3 Alter the LPC to change the positions or bandwidths of the formants to your desired characteristics e By doing this you modify the filter effectively changing the tongue shape and associated resonances used to initially produce the vowel 4 Filter the reconstructed source created in step 2 using the altered LPC from step 3 Performing Source Filter Resynthesis of a vowel in Praat 1 Isolate a vowel in a single
80. the top bar split by the cursor or selection when clicked will play the corresponding pieces of the visible portions of the sound file Hitting lt tab gt also plays the visible portion of the file Obviously to view some analyses and to get a closer look at your data you ll need to use the five buttons in the bottom left corner of the window As you can imagine all shows the entire file in and out zoom in and out sel zooms to make the current selection fill the window and bak zooms back to the previous zoom level For longer sound files in order to view analyses like the spectrogram and formants you ll need to zoom in to show only a pre defined amount of timel The Group setting in the bottom right corner of the window will ensure that if two sounds are open in Editor windows at once they ll share the same zoom characteristics This is best used to compare two versions of the same file say an original versus one with an acoustic modification made All of the measures discussed in this section will use the Editor window and you will spend much of your time working with Praat here so any time spent gaining familiarity will be repaid in spades 6 1 1 Pulling out a smaller section of the file for analysis Although zooming in and out will get you most of the way there it s often useful to isolate a section of a sound usually a single word or vowel into a different Sound object To do this select a portion of a sound say a vo
81. thing desmoothing can be accomplished when creating Intensity objects by altering the minimum pitch value in the Objects To Intensity dialog box That said in most recordings made for phonetic research absolute intensity measures as given by Praat are largely meaningless To accurately measure the absolute intensity of a speaker s voice a sound attenuated booth with a calibrated sound level meter or calibrated microphone with specialized software should be used 22 Relative intensity say between two segments or words can be measured with an uncalibrated microphone but is only accurate if the recording is made in a consistently quiet area and the speaker stayed in the same general position relative to the microphone throughout the recording s and wouldn t have changed much during the time between the two points of comparison This issue is discussed in depth in Praat s user manual 6 7 1 Units of Intensity dB vs Pascal Praat uses two measures of intensity Pascal and dB Pascal tend to be very small numbers like 0 00033082594541105064 whereas dB measurements are far larger yielding numbers like 59 23328336655995 Often when scripting or making measurements of intensity of a section through the interface we want information in dB but selecting Objects Query Get mean to get Mean intensity gives us the information in Pascal In order to get minimum maximum or mean intensity in dB we must first convert
82. tings Praat will happily find you formants even in fricative noise or silence and because it doesn t know how many formants it should be searching for where it commonly merges F and F for high back vowels where they re close gt Q together In addition Praat will often have issues finding a single timepoint so if you re getting an unusual measurement a timepoint shortly before or after may be Danger more accurate Always sanity check your measurements make sure you know what you re measuring and during automated measurement always run the results by a trained human first 21 6 6 3 Scripting Only Formant Objects If you re not scripting disregard this section Working from a formant object will win you nothing in a human centric workflow When scripting you may want to create a Formant object select the sound then Objects Formants amp LPC To Formant burg specifying the proper settings as described above so that you don t need to open the editor to measure formants Once a formant object is created you can instead select the Formant object and run any of the commands in the Objects Query menu to get information Oddly formant measures taken at the same timepoint and with the same settings from a for mant object and from the editor window do not always agree and in fact can differ signifi cantly If measuring formants automatically you may consider using both methods the formant object and the edito
83. tml Penn Phonetics Lab Forced Aligner P2FA http www ling upenn edu phonetics p2fa or Easy Align http latlcui unige ch phonetique easyalign php 53 4 Praat scripts can t sanity check their data e You know fully well that F for i is unlikely to be at 8 000 Hz Praat doesn t You can build in safeguards but Praat will allow all sorts of craziness if left to its own devices 5 Praat scripts can t do anything that you couldn t eventually do through the user interface of Praat e Praat scripting depends on Praat s built in commands so you can t do something that the program was not designed to do That said you can string many commands together to create new commands and processes and you can certainly make things easier for yourself To do anything vaguely scripty in Praat you ll use the Praat menu in the menubar on a Mac at the top of the objects window on a PC and choose New Praat Script to open the scripting editor 11 1 1 Praat s scripting tutorials Perhaps the most useful part of Praat s documentation is the Scripting tutorial accessible through Objects Help Praat Intro Scripting or through the Script Editor window Because these tutorials are so excellent at explaining the peculiarities and structures of Praat s script ing language this document will skip many of the topics discussed there focusing instead on overall usage 11 1 2 Praat scripts vs Editor script
84. ts gt Convert Convert to Mono e This will then collapse both tracks back into a single mono track This will often work and if it does that s wonderful If you end up with odd or undesirable re sults from this move onto the next section and combine the two sounds using a formula 7 10 Formula Modification Waveform addition subtraction and so much more Praat is quite capable of doing sample by sample mathematical operations on both individual files and on pairs or groups of files This is done using one of the most obtuse yet most powerful functions available in Praat Objects Modify Formula function Formula modification is best visualized by thinking about digitized sound Remember that when sound is digitized the waveform itself isn t saved but instead the waveform is sampled at the sampling rate leaving you with a series of times and the amplitude of the wave at that moment So to add two digitized waveforms you simply move through the file sample by sample and compare each sample During waveform addition if at the 31st sample e g the amplitude of Waveform A is at 28 and Waveform B is at 5 you add those two timepoints together 28 5 and in your resulting sound file the 31st sample will have an amplitude of 23 Because this moves sample by sample both sounds will need to have the same sampling rate and need to be of the same length Unfortunately formula combination of sounds is among the le
85. ts of other scripts as you work on your own Also it s worth noting that one of the best ways to learn how to code is to find a script see how it works in terms of what it does by running it and then looking at the script s code to find out how it does what it does Once you ve started collecting scripts you ll find yourself reaching for certain chunks of code every time you say want to open and analyze every file in a given folder or need to generate a plot showing nasality in a given word To that end along with this handout there should be a script called DemoScript praat and its uncommented friend DemoScriptNoComments praat This is a very basic formant mea surement script that takes in TextGridded sound files and spits out the formant readings for 74 those files This script was written specifically to be used for learning and cannibalism and is commented heavily It s also included as an appendix to this document In short the more time you spend nosing around scripts the better 11 6 Closing Remarks on Praat scripting Scripting can very quickly start to save you some time and as such the payoff for even a small amount of work can be great However to get really incredible results and to trim hours off of your measurement tasks you ll need to put more time in You ll need to code then code some more then go steal somebody else s code then re code it because they did it wrong Then you ll need to spend lo
86. ts of time with Praat s tutorials then spend lots of time on the Praat users list You ll add and remove quotes until you never want to see one again and add loops until you re blue in the face But then finally that one script that you ve been working on forever will work You ll start it fill in the form and it will run like a cheetah after a hyperactive gazelle And it ll run the next time And the time after that And each time you start up your script it ll keep running and you ll see the time savings mounting Then eventually you ll realize that all that time that agony totally paid off and rather than spending the afternoon taking measurements you can just start a script running to do it for you then go actually enjoy your life That my friends is why we Praat script References 1 MChen Acoustic correlates of English and French nasalized vowels The Journal of the Acous tical Society of America 1997 2 M Gordon and P Barthmaier A cross linguistic acoustic study of voiceless fricatives Journal of the International Phonetic Association 2002 3 M Gordon and Peter Ladefoged Phonation types a cross linguistic overview Journal of Phonetics 2001 4 Jane Stuart Smith Empirical evidence for gendered speech production s in Glaswegian Laboratory Phonology 9 Phonology and phonetics Jane Cole and Jose Ignacio Hualde eds Mouton de Gruyter New York USA August 2007 pp pp 65 86 75 5
87. tself and are your way of getting information from the user Forms can be used to tell the script how to run specify op tions or have the users input starting information say pitch ranges or the number of measures per vowel These let more complex scripts get user feedback before and while they do what they do best For an example starting form please see Figure 15 Forms are created with blocks of code like the below form Label for the form comment what you re asking the user for 67 800 Calculate Al PO P1 duration for labeled in Tiers in the TextGrid for voweltier 1 o wordtier 2 Sound file extension file type wav gt Around what frequency should look for P1 plsearch 950 How many measures per vowel 1 for midpoint only 3 for start mid end tpnum 5 Automaticity autorun _ Two Pass GraphDump will not work Manual Full human control e Fuli Auto No Human Intervention Dump a PDF graph for each C graphdump Iterate Pulses or use actual vowel A iterate Scoot in how much in seconds from each edge scoot 0 010 Standards Cancel Apply fox Figure 15 An example of a startup form from the CU Nasality Measurement Script 68 000 Label for the form what you re asking the user for your suggestion for what they type in Another request but this lets them assign a number for each choice vowel 1 word 2
88. ty dB vs Pascal A ie BRR Ee Se Heese Cane I esa INN Aa ed J earn boleh a Ba eee a eee e Bae ece sy 6 10 Measuring Harmonic Amplitude Frequency oo oo o 6 11 Measuring Creakiness and Breathiness using Spectral Tilt 6 12 Measuring Nasality using A1 PO 6 13 Measuring Spectral Center of Gravity 7 Creating and manipulating sound Files in Praat eee 7 2 Cropping Copying Splicing and Pasting 7 3 Sampling rates and Resampling eRe A ne pa ae 7 4 1 Low pass filtering 7 4 2 High pass filtering 7 4 3 Band pass notch filtering 7 5 Pitch Manipulation To Manipulation 7 6 Matching the pitch tracks of two sounds 7 7 Manipulating Duration Slowing Down and Speeding Up Sounds 7 8 Matching Intensity 7 9 Combining Sounds 7 10 Formula Modification Waveform addition subtraction and so much more 7 11 Synthesizing Sounds from scratch 7 12 Source Filter Vowel Resynthesis 8 Exporting images for use and publication 8 1 Creating Complex Displays 8 1 1 Overlaying Plots 8 1 2 Multiple Plots in the Picture Window oo ooo 9 Annotating Sound Files Praat TextGrids 10 Using Log Files 11 Scripting in Praat 11 1 What is Praat scripting 11 1 1 Praat s scripting tutorials 11 1
89. veform 2 Select a sound then Objects Draw Draw e Edit the parameters to zoom to the portion you need 3 Use the Picture gt Margins menu to add labels text and other garnishes 4 Select the still blank portion of the picture window which you want to contain the spec trogram 5 Select the sound Objects Spectrum To Spectrogram e Set the Spectrogram settings using the same settings you would in the Editor win dow see Section 6 2 6 Select the newly created Spectrogram object then Objects Draw Paint e Set these parameters as you d like 7 Use the Picture gt Margins menu to add labels text and other garnishes 8 Use the Picture window selection to surround everything in the window for export 9 Use Picture File Save as PDF file to export your picture By doing this you can create entirely within Praat a whole matrix of plots which show all the various facets of a given sound all without resorting to external photo editors 9 Annotating Sound Files Praat TextGrids Praat can t reliably tell where one word starts and where another ends Nor can it find the specific segment you re looking for nor identify the vowel in the word As such you ll often need to segment sound files with that information when using any sort of automated measure ments In Praat this is done by creating TextGrid annotations in a TextGrid file which is saved separately from the sound itself 46
90. wel and then Editor File Extract Selected Sound time from 0 This will create a new sound in the Objects window containing just the selected part of the original sound The preserve times option in the same Editor File menu just keeps the timecode on the extracted sound the same as in context so if the vowel starts at 0 245 s the extracted sound file will start at 0 245 s This can also be done from the objects window using Objects Convert Extract part This amount of time can be changed in Editor View Show Analyses Longest analysis 20 seconds is a sane value for most modern computers much higher will cause your system to lag when viewing files 12 ere Spectrogram settings View range Hz 5000 0 Window length s 0 005 Dynamic range dB 50 0 all of your advanced settings have their standard values your time step strategy has its standard value automatic Help Standards Cancel Apply cos Figure 3 Praat s Spectrogram Settings 6 2 Adjusting the Spectrogram settings Although the basic 0 5000 Hz broadband spectrogram will suffice for many uses it s useful to be able to change those settings To make changes to the spectrogram settings Editor Spectrum Spectrogram Settings This will pull up the Spectrogram settings window like that in Figure 3 The most important settings here are the window length and view range View
91. y the time sampling frequency number of channels and such as you desire To create a complex sound with 1 dB components at 250 and 1000 Hz 1 Objects New Sound Create sound from formula e Under formula enter 1 2 sin 2 pi 250 x sin 2 pi 1000 x e Specify the time sampling frequency number of channels and such as you desire For more information see the Praat Help guide s excellent Formulas Tutorial To create a sound with harmonics use Objects New Sound Create sound from tone complex 7 2 Cropping Copying Splicing and Pasting It s not unusual to need to move remove or copy sound within and across different sound files and luckily Praat makes that relatively easy Most file editing is done with a combination of selection copying and pasting However producing quality splices is not as straightforward as copy and pasting within a word document Because sound waveforms are continuous you need to make sure that all the cuts you re making occur at the same point in the cycle namely at the zero crossing Failure to do so will result in loud pops or clicks in the resulting file To ensure that you re being zero crossing friendly following the below steps substituting Ctrl the control key for Cmd the command key if you re using a Windows or Linux machine To copy paste a portion of the soundfile 1 Select the portion of your soundfile that you d like to copy Editor Select
92. you are getting pitch doubling decrease it if you are failing to track actual rapid changes in Fp e Voiced unvoiced cost Increasing this number will make Praat more reluctant to claim a transition between voicing and voicelessness Turn this up if your pitch track is cutting in and out more 17 than is reasonable Praat s pitch tracking is a good way to get a rough idea of what s going on with the speaker s Fo but relying on it to give you sane measures is not wise especially in os scripts Make sure you sanity check any measures which seem unreasonable against single cycle Fy measurements or against harmonic frequencies and that you throw Danger 2 out anything completely ridiculous 6 4 5 Scripting only Creating a Pitch Object If you re not scripting disregard this section Working from a pitch object will win you very little in a human centric workflow When scripting you may want to create a Pitch object select the sound then Objects Analyze Periodicity To Pitch specifying the proper range so that you don t need to open the editor to measure pitch Once a pitch object is created you can instead select the Pitch object and run Objects Query Get value at time to find the pitch at whatever time you d like Pitch in a pitch object is calculated in the same way as in the Editor window so the same disclaimers apply 6 4 6 Getting Maximum Minimum and Average pitch for a section of spe

Using Praat for Linguistic Research

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