AUDIOPHILE Configuration Software User`s Manual
Contents
1. To save time configuring control settings in the AUDIOPHILE control settings complete setups previously stored may be recalled from disk files with a few simple mouse clicks Open a setup from a disk file as follows 1 Click on File on the AUDIOPHILE menu bar When the pull down menu appears click on Open Settings File Alternatively click on the ay icon on the toolbar This will cause the following window to appear Open Settings File Look in Audiophile ek Ez E Drivers EG E default aps My Recent 1 Factory Defaults aps Documents Desktop My Documents My Computer M p etwork File name i aces Files of type Audiophile Settings aps Cancel Figure 4 1 Open Settings File Window 2 Once the desired setup file name has been found either double click it or select and click on Open to recall it The file will be loaded into both the software and the hardware NOTE Opening a setup file DOES NOT update the flash memory in the AUDIOPHILE hardware If you want the loaded parameters to continue to be applied after the Command Center software is exited you will need to use the Program feature NOTE The file Factory Defaults aps contains the original parameters loaded into the AUDIOPHILE unit at the factory Therefore you can always restore the AUDIOPHILE to factory original condition simply by opening this file and re programming the flash memory 5 0 ONE CHANNEL ADAPTIVE FILTE2. or adjusting the Voice Limit settings so that some frequencies that had been heavily Lower and Upper Voice Limits attenuated are now present While the settings changes will take effect immediately the Auto Gain may take some time to adapt to the change For this reason when the user expects to be making many changes in the settings it is often better to disable Auto Gain and instead choose a manual gain setting that avoids clipping The Lower and Upper Voice Limits allow the user to specify the frequency range or ASIF region over which the ASIF is applied Two red markers controlled by the sliders below the display trace indicate where the lower and upper voice limits are located The markers may also be adjusted by clicking and dragging within the display trace Viewing audio on the display trace while manipulating the markers is an easy way to identify where your ASIF region limits should fall Typically the ASIF region is chosen to be the range over which speech frequencies are found Setting a Lower Voice Limit above 300 Hz or an Upper Voice Limit below 3000 Hz is not recommended as intelligibility may suffer All frequencies outside the ASIF region are assumed to be non speech and are therefore attenuated 18 0 VOX ALGORITHM The smart VOX algorithm as implemented in the AUDIOPHILE is functionally illustrated in Figure 18 1 The input audio is initially bandpass filtered to select the spectral segment whi
3. Cutoff Frequency is 0 Hz while the maximum Lower Cutoff Frequency Upper Cutoff Freguency Transition Slope Stopband Attenuation is 10 Hz below the Upper Cutoff Frequency Lower Cutoff Frequency can be adjusted in 1 Hz steps NOTE The Lower Cutoff Frequency can never be set higher than 10 Hz below the Upper Cutoff Frequency Specifies frequency in Hertz above which no signals are attenuated Frequencies between this cutoff and the Lower Cutoff Frequency are attenuated Minimum Upper Cutoff Frequency is 10 Hz above the Lower Cutoff Frequency while the maximum Upper Cutoff Frequency is 8800 Hz Upper Cutoff Frequency can be adjusted in 1 Hz steps NOTE The Upper Cutoff Frequency can never be set lower than 10 Hz above the Lower Cutoff Frequency Specifies slope at which frequencies above the Lower Cutoff Frequency and below the Upper Cutoff Frequency are attenuated in dB per octave Sharpest attenuation occurs when Transition Slope is set to maximum while gentlest attenuation occurs when Transition Slope is set to minimum Note that the indicated value changes depending upon Cutoff Frequency and Configuration Also note that the Lower and Upper Transition Slopes always have different values this is because the frequency width of an octave is proportional to Cutoff Frequency Specifies amount in dB by which frequencies above the Lower Cutoff Frequency and below the Upper Cutoff Frequency are attenuated Stopband attenu
4. Filter 2 Filter 1 and Filter 2 are identical FIR stages each having one of nine possible filter types available for use selectable via drop down menu These are One Channel Adaptive Filter 512 taps maximum Lowpass Filter Highpass Filter Bandpass Filter Bandstop Filter Comb Filter Notch Filter Slot Filter Pass Thru Filter Filter 1 1 CH Adaptive y Enable Figure 2 2 Filter 1 Filter 2 Controls Once the filter type is selected click on the Config button to bring up the detailed control window for the selected filter This allows you to customize the parameters that define the filter performance After selecting the values for each parameter click on the OK button to close the window In the case of the 1 CH Adaptive filter an additional Clear button will appear on the screen this allows user resetting of the adaptive filter Finally there is an Enable checkbox available when checked the filter stage is being applied to the audio signal but when un checked the filter stage has no effect Refer to Chapters 5 13 for more information on the specific filter types and their parameters 2 4 Broadband Stage The Broadband Stage controls are illustrated below Broadband Stage mount 68 J Enable Figure 2 3 Broadband Stage Controls Following Filter 1 and Filter 2 the Broadband Stage implements a spectral subtraction noise reduction process on the audio signal which can be very effective at reducing any
5. exactly 50 or 60 Hz due to tape speed errors Next adjust the Notch Limit down in frequency until the hum is barely heard then increase it 100 200 Hz Adjust the Notch Depth up following the same procedure Finally select the Odd or Even if they do not increase the hum level otherwise use All This procedure minimizes the filtering to only that needed for the hum Since a comb filter is a reverberator a 1CH Adaptive Filter is often placed after it to reduce the reverberation and clean up any residual noises escaping the comb filter A graphical description of the Comb filter and its controls follows in the figure below Transfer Functions of a 60 Hz Comb Filter Having 40 dB Notch Depth and 300 Hz Notch Limit Attenuation dB All Harmonics M pe Se s EN Frequency Hz 30 30 240 300 B Attenuation dB Even Harmonics Frequency Hz Attenuation dB S Odd Harmonics Figure 10 2 Comb Filter Graphical Description CAY Page 37 11 0 NOTCH FILTER Application The Notch filter is used to remove or notch out a narrow band noise such as a tone or a whistle from the input audio with minimal effect to the remaining audio The Notch filter works best with stable noise sources which have constant freguency if the freguency of the noise source varies then the 1CH Adaptive filter is recommended To properly utilize the Notch filter you will first need
6. non speech background audio detected in the signal Because the effects of the processing are potentially very harsh a filter Amount slider control is provided which can be set to any value between 0 no noise reduction and 100 maximum noise reduction Typically setting to control to approximately 70 provides the best balance between good background noise reduction and minimal induced artifact in the voice signal See Chapter 14 for more detailed information on the Broadband Stage noise filter algorithm 2 5 Equalizer Stage The Equalizer Stage controls are illustrated below Equalizer Stage Adaptive SIF w Enable Figure 2 4 Equalizer Stage Controls Following the Broadband Stage the Equalizer Stage applies the specified equalization method to the audio signal Three different equalization methods are available for use These are e 20 Band Graphic Equalizer e Hi Res Graphic Equalizer e Adaptive Spectral Inverse Filter automatic equalizer Once the equalizer type is selected click on the Config button to bring up the detailed control window for the selected equalizer This allows you to make adjustments as desired for best sound and intelligibility After adjusting click on the OK button to close the window In the case of the Adaptive SIF an additional Clear button will appear on the screen this allows the user to reset the algorithm and re equalize from scratch Finally there is an Enable checkbox available wh
7. rate setting controls the update rate for the spectral average which in turn determines how quickly the filter responds to changes in the input audio Upper and Lower Voice Limit controls allow the user to specify the range over which equalization is applied The amount of spectral correction 0 100976 as well as the amount of gain applied to the final output is adjustable using the Filter Output controls The user can enable the Auto Gain functionality to ensure that the output audio level is automatically maintained at approximately the same as the input audio level If the user disables the Auto Gain the output gain slider is available to manually boost the level of the output signal Adaptive Spectral Inverse Configuration Voice Limits Dutput Shape Filter Output O Flat Pink O Voice Custom Edi Enable Auto Gain Figure 17 1 ASIF control window Description of controls indicators is as follows Adaptation Clear Button Adapt Rate Control Used to specify the adaptation rate of the averager on which the ASIF is based Smaller values cause the averager and hence the filter to update more slowly whereas larger values allow faster update Use a value of 0 01 approximately mid scale for most applications This button allows the user to re initialize the ASIF response and restart adaptation NOTE After a Clear operation there will be an adaptation period while the filter adapts to the current inp
8. AUDIOPHILE Front End Audio Processing and Voice Detection System CONFIGURATION SOFTWARE USER S MANUAL Version 1 3 Audiophile Command Center File Hardware Help z E Filter 1 1 CH Adaptive v NI tection Threshold 7 dB defaut vi j Pre event time 1 sec Enable Broadband Stage VOX v Post event time 5 secs v v Speech Activity Equalizer Stage AGC Maximum Gain Adaptive SIF v OdB Bypass Config Config 10dB v Enable Clear O 20dB v Enable 30d8 Digital Audio Corporation a DRI company 4018 Patriot Drive Suite 300 Durham NC 27703 AUDIOPHILE Front End Audio Processing and Voice Detection System CONFIGURATION SOFTWARE USER S MANUAL Version 1 3 June 13 2006 Document Number 060317ADT Digital Audio Corporation a DRI company 4018 Patriot Drive Suite 300 Ee NC 27703 Phone 919 572 Fax 919 572 eres sales dacaudio com www dacaudio com Copyright 2006 by Digital Audio Corporation All rights reserved TABLE OF CONTENTS De OWS VTE sence coe TA AE AA RE OE N 6 EU iese ld ee APE OE Canas 6 jEA c er PIE 7 2 0 AUDIOPHILE CONFIGURATION CONTROL eee 13 2 1 AUDIOPHILE Command Center eene 13 2 2 CUStOmizirigdll els o dio odio od iod AE tini he el mds 13 23 i e 14 2 4 Broadband Stage EE EE eee ee eee Oe ee RG MM Du E 15 25 CUANZA uoo Fo Fah hha ha teet Dh Pot tot mu
9. Controls for the VOX algorithm are described in Chapter 2 6 NOTE the Pre event time control places a constant audio delay on the signal flowing through the AUDIOPHILE regardless of whether the VOX is enabled or disabled This means that whenever the filter controls are adjusted you will have to wait the specified Pre event time value for the effect to become audible Should you wish to hear the effects of the filter controls instantly during initial filter setup you can temporarily set the Pre event time to 0 while setting up the filtering then change it back to the desired value prior to programming the AUDIOPHILE 1MdIno e xD aun euin jue e sog ue 8 8Jd 10 e19U99 ETA A Er SUOL O 91607 uonoejeq 2910A NN his a NI eoue s ad ALIALLOV HOdddS Joyedwog 3q 99I0A MD 9 P in N aun keja Ed juana ald ploysayl A jejeq 19114 ER 490 4 SWIZE 19114 2 INS Bulujoows 91 sel JO e ul ABlaug ssedpueg M i NIN 3 winwiui l 1NdNI Figure 18 1 VOX Algorithm Block Diagram CAY Page 54 19 0 AGC ALGORITHM Application The Automatic Gain Control boosts low level output signals to a peak reference level 18dB below full scale output or 18dBFS by gradually increasing output signal gain until either the proper level or Maximum Gain has been reached This compensates for near party far party conversations and for losses in signal level which may have occurred during the enhancement process lf the output
10. IF v DdB Bypass Config Config 10 v Enable O 30dB Figure 2 1 AUDIOPHILE Command Center At the top of the AUDIOPHILE Command Center window is a Menu Bar From the File menu item you can choose to Open a filter settings file Save filter settings to a specified file name or Exit the software From the Hardware menu item you can Program settings to the AUDIOPHILE internal flash memory Connect or Disconnect the USB communications with the unit and select an option to Synchronize To Hardware On Connect From the Help menu item you can view the Contents of this help file not yet available in version 1 0 or read information About the AUDIOPHILE software Below the Menu Bar is the Toolbar Each small icon allows a quick shortcut to some of the Menu Bar items Each icon represents the menu function of Open Save and Program the AUDIOPHILE respectively 2 2 Customizing Filters The AUDIOPHILE Command Center allows all audio processing settings to be configured using interactive software controls while connected to the AUDIOPHILE hardware via USB connection One all settings configured as needed for the application they can be stored to the internal flash memory using the Program feature There are multiple stages of audio processing that are available for use The signal flow from input to final output is as follows Filter 1 Filter 2 Broadband Stage Equalizer Stage VOX AGC 2 3 Filter 1 and
11. R Application The 1CH Adaptive filter is used to automatically cancel predictable and convolutional noises from the input audio Predictable noises include tones hum buzz engine motor noise and to some degree music Convolutional noises include echoes reverberations and room acoustics One Channel Configuration Prediction Span Adapt hate Auto Normalize Filter Size 512 taps max Processor Output Normal Rejected Figure 5 1 1CH Adaptive Filter Control Window Description of controls is as follows Filter Size Adapt Rate Used to set the number of FIR filter taps filter order in the adaptive filter Filter size is indicated both in taps and in milliseconds Minimum Filter Size is 1 tap but can be set to as high as 512 taps Small filters are most effective with simple noises such as tones and music Larger filters should be used with complex noises such as severe reverberations and raspy power hums A nominal filter size of 256 taps is a good overall general recommendation Used to set the rate at which the adaptive filter adapts to changing signal conditions Mathematically known as Mu A Mu of 1 provides very slow adaptation while a Mu of 5884 provides fastest adaptation CAN Page 24 Auto Normalize Prediction Span Processor Output Clear Button Larger adapt rates should be used with changing noises such as music whereas smaller adapt rates are acceptable fo
12. ation is adjustable from OdB to 120dB in 1 dB steps A graphical description of the Bandstop filter and its controls follows in the figure below Attenuation dB Lower Transition j Slope EDEN Upper Transition Slope dB Octave dB IE e Octave gt topband Attenuation dB Lowe Lower Passband Transition Band Uppe Transition Upper Passband Band Lower Upper Cutoff Cutoff Frequenc Freduene Frequency Hz Figure 9 2 Bandstop Filter Graphical Description 10 0 COMB FITLER Application The Comb filter is used to remove or notch out harmonically related noises noises which have exactly equally spaced frequency components such as power line hum constant speed motor generator noises etc from the input audio The filter response consists of a series of equally spaced notches which resemble a hair comb hence the name Comb filter Adjust the Fundamental Notch Frequency to the desired spacing between notches also known as fundamental frequency Set the Notch Limit to the frequency beyond which you do not want any more notches Set the Notch Depth to the amount in dB by which noise frequency components are to be reduced Normally the Notch Harmonics option will be set to All causing frequencies at all multiples of the Fundamental Notch Frequency within the Notch Limit to be reduced However certain types of noises have only the odd or even harmonic components p
13. attenuation is adjustable from OdB to 120dB in 1 dB steps Specifies slope at which frequencies above the Cutoff Frequency are rolled off in dB per octave Sharpest roll off occurs when Transition Slope is set to maximum while gentlest roll off occurs when Transition Slope is set to minimum Sharp roll offs may cause the voice to sound hollow but will allow more precise removal of high frequency noises Note that the indicated value changes depending upon Cutoff Frequency A graphical description of the lowpass filter and its controls is given below Attenuation dB I e A lt Transition Slope M Stopband As Attenuation tal E A E Passband Transition Stopband dB Band i 7 V di Frequency Hz Frequency Hz ERA Figure 6 2 Lowpass Filter Graphical Description 7 0 HIGHPASS FILTER Application The Highpass filter is used to decrease the energy level lower the volume of all signal freguencies below a specified Cutoff Freguency thus reducing low freguency noises such as tape or acoustic room rumble from the input audio The Highpass filter is sometimes called a rumble filter The Cutoff Frequency is usually set below the voice frequency range somewhere below 300 Hz so that the voice signal will not be disturbed While listening to the filter output audio the Cutoff Frequency initially set to 100 Hz can be incrementally increased until the quality of the voice just begins to be aff
14. ch gives preference to voice energy This filter is centered at 200 Hz and has a 500 Hz bandwidth The average energy E is then computed for each 32 msec segment of bandpassed audio The algorithm then compares the average energy E with two time varying reference levels These levels are based on the smoothed minimum values of E Each 512 msec the minimum value of E which would be the smallest of the most recent 16 E values is computed This minimum value MIN is then smoothed using a lowpass filter with a long time constant approximately 9 seconds The voice detect level Lp consists of SM the smoothed MIN values plus the voice Detection Threshold THp specified by the Command Center software If E exceeds this voice detect level the algorithm considers this to be a speech event and the SPEECH ACTIVITY LED an indicator provided only in the Command Center software will be illuminated When a speech event occurs the logic assumes that the voice occurred before and after the detection Pre event time and Post event time values as specified by the Command Center software are applied to each detection thereby expanding it in time in both directions During speech the detections typically occur frequently enough for the overlaps to form a continuous stream of detected speech which is then passed to the control logic When speech is not detected the VOX algorithm will output either Silence no audio output or C Tone as specified
15. d 15 20 VOA EE 16 2 1 Automatic Gain Control eee EE iie iaei 17 2 8 Programming the AUDIOPHILE assets eed sede be redes ee dee Be ve des be eise de 17 2 9 Synchronization Options as SE SE D Ih D ech D D ce ee 19 3 0 STORING FILTER CONFIGURATIONS ee ee ee ee ee ee ee ee ee ee Re ee ee ee ee ee ee ee ee ee 20 3 1 Save File Dialog BOX se site hei fea iod ii iii onde 20 4 0 RECALLING FILTER CONFIGURATIONS HH He 22 4 1 Open File Dialog BOX sti ebbe op pp Dp BD And 22 5 0 ONE CHANNEL ADAPTIVE FILTER eee 24 6 0 LOWPASS FILTER 03000100750 26 TO HIGHPASSEILTER ouere Idioma nina iem ionis ee 28 8 0 BANDPASS EIETER 10000000 Eg Re tee 000205 EE Ge Re a iain 30 9 0 BANDS OP FILTER oee ett a eue esto de AG eet tee ost ute a eg ee 33 10 0COMB A A O rhe heben 35 TEO NOTEHEILTER orita did ends tend 38 12 0 SLOT FILTERS o Ge ree 40 13 0 PASSTHROUGH FILTER coi 42 14 0 BROADBAND STAGE etica 43 15 0 20 BAND GRAPHIC EQUALIZER eene 44 16 0 HI RES GRAPHIC EQUALIZER eene een 46 17 0 ADAPTIVE SPECTRAL INVERSE PI TE Rias 48 18 0 VOX Eco susse sesse A ag RD GE bs 53 19X0 AGCALGORITHM M 55 LIST OF FIGURES Figure 2 1 AUDIOPHILE Command Center iese esse sesse dee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee 13 Figure 2 2 Filter 1 Filter 2GontOIS EE ESE EE ES EE EE EE GE EG EE EG GE ee Ee erect 14 Figure 2 3 Broadband Stage Controls ies
16. dB bs N Slot Width Stopband Attenuation dB Slot EER Frequency Hz Figure 12 2 Slot Filter Graphical Description 13 0 PASSTHROUGH FILTER Application The Passthrough Filter is used to pass the audio through the filter stage unaffected lt is often used when one stage of the AUDIOPHILE filter is not needed for whatever reason Filter 1 av Contig Enable Figure 13 1 Pass Thru Filter Selection There are no control options for a Passthrough filter The Config button is deactivated when the Passthrough filter is selected for a stage 14 0 BROADBAND STAGE Application The Broadband Stage is a frequency domain spectral subtraction filter that implements automatic noise reduction over 128 separate frequency bands It operates by continually measuring the spectrum of the input signal and attempting to identify which portions of the signal are voice and which portions are non voice or noise All portions determined to be noise are used to continually update a noise estimate calculation this is used to calculate the equalization curve that needs to be applied to the input signal to reduce each band s energy by the amount of noise energy calculated to be in that band The net result is an output signal that has all non voice signals reduced in level as much as possible thereby polishing the enhanced voice signal as much as possible prior to final equalization and AGC Operat
17. e esse ese ede ee ee ee ee ee ee ee ee ee ee ee ee 15 Figure 2 4 Equalizer Stage Controls ees esse ees ee ee ee ee ee ee ee ee 15 EA de CONTOS EE EE EE N ERR EE 16 Figure 2 6 AGCControls EE EE RE ER RE ee eee 17 Figure 2 7 AUDIOPHILE Front Panel USB ConnecCtOF esse esse sesse ee ee ee ee ee ee ee ee 18 Figure 2 8 AUDIOPHILE Communications Error Message esse esse ee ee ee ee ee ee ee ee ee ee ee 18 Figure 3 1 Save As Setup File WindOW sesse ese nee GR Ee ER eed Ge Re de Ge GE ee GR Ge ee ed Ge ee ede Ke ee 20 Figure 4 1 Open Settings File Window ccccccccccsceesesesteeeeseeeeeseeeeeeeeeeeeeeeneeeeeeeeeseeceese 22 Figure 5 1 1CH Adaptive Filter Control WindOW ees ees ees ese ee ee ee ee ee 24 Figure 6 1 Lowpass Filter Control WindOW ese ee ee 26 Figure 6 2 Lowpass Filter Graphical DescriptiON esse ee ee ee RR ee ee ee ee ee ee 27 Figure 7 1 Highpass Filter Control WindOW ees ees ee ee ee ee 28 Figure 7 2 Highpass Filter Graphical Description esse see ee ee ee ee ee RR ee ee ee ee ee ee 29 Figure 8 1 Bandpass Filter Control WindOW ese ee 30 Figure 8 2 Bandpass Filter Graphical Description esse ee ee ee ee RR Ee ee ee ee ee ee 32 Figure 9 1 Bandstop Filter Control WindOW ees esse ee ede ee ee ee ee ee ee ee ee ee ee ee ee ee 33 Figure 9 2 Bandstop Filter Graphical DescriptiON esse ee ee ee RR RE ee ee ee ee ee 34 Figure 10 1 Comb F
18. e installation program will then start Step 1 The InstallShield Wizard will open and inform you that it s about to install Audiophile Command Center on your computer Click Next ie Audiophile Command Center InstallShield Wizard Welcome to the InstallShield Wizard for Audiophile Command Center The InstallShield R Wizard will install Audiophile Command Center on your computer To continue click Next WARNING This program is protected by copyright law and international treaties Step 2 The Audiophile Command Center software will be installed into your Program Files directory Click Install ie Audiophile Command Center InstallShield Wizard Ready to Install the Program The wizard is ready to begin installation IF you want to review or change any of your installation settings click Back Click Cancel to exit the wizard Current Settings Setup Type Typical Destination Folder C Program Files Digital Audio Corporation Audiophilel User Information Name Company InstallShield Step 3 The software will copy itself into the appropriate directory Click Finish when it completes CAY Page 8 ie Audiophile Command Center InstallShield Wizard InstallShield Wizard Completed The InstallShield Wizard has successfully installed Audiophile Command Center Click Finish to exit the wizard Step 4 After Finish is clicked you will see a command line window pop up for a few seconds and
19. ected achieving maximum elimination of low frequency noise The amount of volume reduction below the Cutoff Frequency can further be controlled by adjusting the Stopband Attenuation setting maximum volume reduction is 120dB The slope at which the volume is reduced from normal at the Cutoff Frequency to the minimum volume specified by Stopband Attenuation can also be controlled by adjusting the Transition Slope setting Highpass Configuration Cutoff Frequency Stopband Attenuation EI Enable Transistion Slope Figure 7 1 Highpass Filter Control Window Description of controls is as follows Cutoff Frequency Specifies frequency in Hertz below which all signals are attenuated Frequencies above this cutoff are unaffected Minimum Cutoff Frequency is 0 Hz no frequencies attenuated while the maximum Cutoff Frequency is 8800 Hz Cutoff Frequency can be adjusted in 1 Hz steps Stopband Specifies amount in dB by which freguencies below the Attenuation Cutoff Frequency are ultimately attenuated Stopband attenuation is adjustable from OdB to 120dB in 1 dB steps Transition Slope Specifies slope at which frequencies below the Cutoff Frequency are attenuated in dB per octave Sharpest attenuation occurs when Transition Slope is set to maximum while gentlest attenuation occurs when Transition Slope is set to minimum Note that the indicated value changes depending upon Cutoff Frequency A graphical description of the highpa
20. elected spectral shape is applied to further reshape the audio spectrum The following output shapes are available Flat no additional shaping after ASIF flattening Pink 3 dB per octave rolloff above 100 Hz is applied in addition to ASIF flattening e Voice 6 dB octave rolloff above and below 500 Hz in addition to ASIF flattening e Custom user draws custom curve to be applied in addition to ASIF flattening Note Changing the output shape does not require an adaptation period to arrive at a good solution Because a full average spectrum is maintained regardless of the output shape setting the new output shape takes effect instantaneously in both the output audio and the display traces However since the auto gain adapts based on the actual applied filter with the shaping curve taken into account there may be some adaptation time required to reach a stable auto gain value after the shaping curve is changed To draw a custom curve select Custom and then click the Edit button beneath the Custom selection button the ASIF Custom Curve window will open Click New to begin a new curve To draw the curve use your mouse to make single clicks within the axes the curve is built piecewise by connecting the dots at the click locations For fine control of the click locations use the cursor coordinate information located at the bottom of the drawing axes The ASIF custom curve drawing window is identical to the Hi Res Graphic Filte
21. elow AGC Maximum Gain 0dB Bypass 10dB 20dB O 30dB Figure 2 6 AGC Controls Following the VOX the AGC implements an audio level compression function that automatically compensates for near far party level differences as well as low level audio signal remaining after the multiple noise reduction stages have been applied See Chapter 19 for more detailed information on the AGC 2 8 Programming the AUDIOPHILE The USB port on the AUDIOPHILE front panel provides the connection between the PC and the AUDIOPHILE which allows software programming and operation of the unit Simply connect the supplied 5 pin mini B cable between the AUDIOPHILE s USB port and any free USB port on your computer and or USB hub making sure the unit is powered on and the supplied software driver will provide the necessary connection USB X Figure 2 7 AUDIOPHILE Front Panel USB Connector With the AUDIOPHILE unit properly connected to the PC the Command Center software will when launched automatically Connect to the hardware and establish communication If for whatever reason this communication cannot be established the following error message will appear Audiophile Communication Error Figure 2 8 AUDIOPHILE Communications Error Message Once the communication has been established the hardware will automatically synchronize to the current state of the software and full interactive software control will commence Any c
22. en checked the equalizer stage is being applied to the audio signal but when un checked it has no effect Refer to Chapters 15 17 for more information on the specific equalizer types and their parameters 2 6 VOX The VOX controls are illustrated below VOX Detection Threshold 7 dB default v Pre event time 1 sec v Post event time 5 secs j O Silence CTone Enable O Speech Activity Figure 2 5 VOX Controls Following the Equalizer Stage the VOX implements a speech activity detection algorithm on the audio signal which when enabled allows subsequently connected recording equipment to record only the portions of the audio signal that contain speech A Speech Activity LED indicator is provided whenever voice is detected this indicator will iluminate GREEN For each detection event audio signal that occurs within the Pre event time prior to the event is considered to be speech as is the audio signal that occurs within the Post event time after the event When the Enable checkbox is checked all non speech sections of the output audio will be replaced with Silence or C Tone as specified by the radio buttons The Detection Threshold allows the user to select how far above the noise floor the signal needs to be before it is considered a voice signal See Chapter 18 for more detailed information on the VOX algorithm 2 7 Automatic Gain Control The Automatic Gain Control AGC controls are illustrated b
23. enu appears click on Save Settings Alternatively click on the m icon on the Toolbar This will cause the following window to appear Save Settings Save in Audiophile ex E3 2 D Drivers ES Ej default aps My Recent Factory Defaults aps Documents 3 Desktop My Documents My Computer My Network File name Places Save as type Audiophile Settings aps se Figure 3 1 Save As Setup File Window 2 You will need to specify a filename for the setup Click on the File Name text box then type the desired filename All setup filenames must have the APS extension thus if necessary the APS extension is automatically appended to whatever name is typed into the text box 3 Click on Save to store the setup file with the selected filename to the specified drive and directory NOTE The file default aps is the configuration file stored in the installation directory that holds the initial startup information for the AUDIOPHILE software Each time the AUDIOPHILE software is run these settings are loaded unless the Synchronize To Hardware option is selected However please also note that the default aps file is NOT automatically re written when the software exits therefore any changes made to the settings while the software is open will not be retained unless explicitly saved to a file by the user 4 0 RECALLING FILTER CONFIGURATIONS 4 1 Open File Dialog Box Application
24. f controls indicators is as follows Filter Display Graphically displays the current shape of the filter Also used in conjunction with the mouse to draw a new filter shape or to edit an existing one A grid is provided to assist the user in visually judging frequency and attenuation at any point in the display Frequency and Used to precisely readout the frequency in Hertz and Level Readouts attenuation in dB at any point in the filter curve 17 0 ADAPTIVE SPECTRAL INVERSE FILTER Application The Adaptive Spectral Inverse Filter ASIF is a fully adaptive equalization filter that automatically readjusts the spectrum to match an expected spectral shape lt is especially useful when the target voice has been exposed to spectral coloration i e muffling hollowness or tinniness and also when the signal has had substantial noise reduction processing applied that may tend to reduce the naturalness of the voice The ASIF maintains an average of the signal s spectrum and uses this information to implement a high resolution digital filter for correcting long term spectral irregularities The goal of the filter is to reshape the overall spectral envelope of the audio not to respond to transient noises and characteristics Several user controls are available for refinement of ASIF operation The user can specify the desired output spectrum Output Shape so that the output audio is reshaped to a flat pink voice like or custom curve An adapt
25. gain of its frequency band to any value between OdB and 100 dB in 1dB steps Center Freguency Gain Indication Normalize Button Zero All Button Reduce All 1dB Button Maximize All Button Note that the Center Frequency of each band is labelled underneath each slider and that bands are more closely spaced at low frequencies Above each slider control the gain for that frequency band is given The gain can also be visualized graphically by the position of the slider control This button instantly shifts all slider controls up together until the top slider is at OdB After normalization the relative positioning of the sliders remains the same This allows the digital equalizer to implement the desired equalization curve with minimum signal loss This button instantly moves the slider controls for all bands to OdB defeating the entire equalizer This is a useful feature when it is desired to reset all sliders from scratch This button shifts all sliders down by 1dB from their current position no slider however will be allowed to go below 100dB This button allows the user to shift the entire equalizer curve down so that there will be room to move one or more sliders up relative to the others This button instantly moves the slider controls for all bands to 100dB causing the equalizer to mute all output This is a useful feature when it is desired to start with no audio output then bring the slider control
26. gh freguency noises such as tape hiss from the input audio The Lowpass filter is sometimes called a hiss filter The Cutoff Freguency is usually set above the voice freguency range so that the voice signal will not be disturbed While listening to the filter output audio the Cutoff Freguency can be incrementally lowered from its maximum freguency until the guality of the voice just begins to be affected achieving maximum elimination of high freguency noise The amount of volume reduction above the Cutoff Freguency can further be controlled by adjusting the Stopband Attenuation setting maximum volume reduction is 120dB The slope at which the volume is reduced from normal at the Cutoff Frequency to the minimum volume specified by Stopband Attenuation can also be controlled by adjusting the Transition Slope setting Lowpass Configuration Cutoff Frequency Stopband Attenuation Transistion Slope mE ET J Enable Figure 6 1 Lowpass Filter Control Window Description of controls is as follows Cutoff Specifies frequency in Hertz above which all signals are Frequency attenuated Frequencies below this cutoff are unaffected Minimum Cutoff Frequency is 0 Hz while the maximum Cutoff Stopband Attenuation Transition Slope Frequency is 8800 Hz Cutoff Frequency can be adjusted in 1 Hz steps Specifies amount in dB by which frequencies above the Cutoff Frequency are ultimately attenuated Stopband
27. hanges made to the processing settings in the Command Center software will have instant audible effect in the AUDIOPHILE hardware in a very similar manner to more sophisticated DAC products such as the PCAP and CARDINAL However please note that the software settings WILL NOT affect the parameters stored in the AUDIOPHILE internal flash memory until the Program feature has been activated There are two ways to program the AUDIOPHILE flash memory 1 Using the Menu Bar click Hardware then Program Settings or 2 Click the EA icon on the Toolbar As a failsafe feature whenever you attempt to Exit the Command Center software without having reprogrammed the flash memory a nag message will appear to remind you that this needs to be done Should you choose not to reprogram the unit please keep in mind that the AUDIOPHILE hardware will revert to its previous flash memory settings after you have exited the software NOTE the AUDIOPHILE always uses its flash memory settings whenever it is not connected with the Command Center software Command Center software settings ONLY become non volatile when the Program feature is activated The hardware unit will always reset itself to the flash memory settings after being disconnected from the software this may have the unintended result of clearing any adaptive filters that may be currently running 2 9 Synchronization Options Whenever the software connects to an Audiophile hardware unit synchron
28. idth of the generated notch in Hertz Adjustment range is 58 2 Hz to 6750 0 Hz TIP A notch filter is best only for very stable tones It has a sharp or V bottom meaning that maximum attenuation only occurs at a single frequency For less stable tones e g those with wow and flutter due to analog recording and playback a flat or square bottom is needed Therefore the Bandstop filter may be preferred Also the 1CH Adaptive filter is useful in tracking varying tones A graphical description of the Notch filter and its controls follows in the figure below Attenuation dB Sa i Notch Width Notch Depth Notch Frequency Frequency Hz Figure 11 2 Notch Filter Graphical Description 12 0 SLOT FILTER Application The Slot filter is used to isolate or slot a single frequency signal such as a tone or a whistle in the input audio attenuating all other audio This is the exact opposite of the Notch filter function To properly utilize the Slot filter you will first need to identify the frequency of the signal to be isolated this is best done using a Spectrum Analyzer Once the frequency of the signal has been identified initially set Stopband Attenuation to 120 dB and the Slot Width to the narrowest possible value Next set the Slot Frequency to the signal frequency Fine adjustment of the Slot Frequency may be necessary to place the slot right on top of the signal This is best done by adju
29. ile the maximum Upper Cutoff Frequency is 8800 Hz Upper Cutoff Frequency can be adjusted in 1 Hz steps NOTE The Upper Cutoff Frequency can never be set lower than 10 Hz above the Lower Cutoff Frequency Transition Slope Specifies slope at which frequencies below the Lower Cutoff Frequency and above the Upper Cutoff Frequency are attenuated in dB per octave Sharpest attenuation occurs when Transition Slope is set to maximum while gentlest attenuation occurs when Transition Slope is set to minimum Note that the indicated value changes depending upon Cutoff Frequency Also note that the Lower and Upper Transition Slopes always have different values this is because the frequency width of an octave is proportional to Cutoff Frequency Stopband Specifies amount in dB by which frequencies below the Lower Attenuation Cutoff Frequency and above the Upper Cutoff Frequency are ultimately attenuated Stopband Attenuation is adjustable from OdB to 120dB in 1 dB steps A graphical description of the Bandpass filter and its controls follows in the figure below Attenuation dB Lower Transition Slope dB Octave A Stopband Upper Transition Slope dB Octc Attenuation Lower PER Lower Stopband Transition Passband dB Band Lower Uppe Cutoff Frequenc Frec Figure 8 2 Bandpass Filter Graphical Description CAY Page 32 9 0 BANDSTOP FILTER Application The Bandstop filter i
30. ilter Control Window oooccccccccccccccccccccnnnonononononononononononononinnninonos 35 Figure 10 2 Comb Filter Graphical Description ccooooooonnccnonccccnnoncononnnnnnnnnnnnns 37 Figure 11 1 Notch Filter Control Window oocccccccccccccccnncccncncnonnnnnnnnnononononononcnnnnnnnnnos 38 Figure 11 2 Notch Filter Graphical Description ees ee RR RR ee ee ee ee ee 39 Figure 12 1 Slot Filter Control VIndOW scs EE DRA ote DE o ig 40 Figure 12 2 Slot Filter Graphical DescriptiON ococcccnnnnnnnnnnccnnnncnononoconanonnnnnnnnnnos 41 Figure 13 1 Pass Thru Filter Selection ie EE rne ERGER SEE DEEG EG ESE OR EE EE EER Gee Ee 42 Figure 15 1 20 Band Graphic Equalizer Control WiNdOW ooooooccccccccccccnnccnoncnnnnnnnnnnns 44 Figure 16 1 Spectral Graphic Equalizer WiNdOW ese ese ee ee ee ee RR Ee ee ee ee ee ee 46 Figure 17 1 ASIF control WINdOW oai tee obere ac e eerte ee de eee ee bte ere Ge Ee 49 Figure 17 2 ASIF custom curve drawing window cccccccccccccccccnnccnnnnnnnnnnonnnnnnninininininoss 51 Figure 18 1 VOX Algorithm Block Diagram esse esse esse ee ee ee ee ee ee 54 1 0 OVERVIEW 1 1 Introduction The AUDIOPHILE Configuration Software allows for complete setup and intuitive interactive control of all the audio processing on the AUDIOPHILE via USB connection between the AUDIOPHILE hardware and a Windows based PC Once properly configured for the application all process
31. ing settings can be saved in the AUDIOPHILE s internal flash memory for stand alone operation without the computer connection The processing configuration can consist of any or all of the following options e Two FIR stages adaptive or fixed up to 512 taps each o Nine different filter types to choose from e Spectral subtraction broadband noise reduction filter o User controllable filter amount 0 100 e Equalizer stage o Three different types to choose from including adaptive spectral inverse e Smart VOX speech activity detection algorithm o Adjustable pre and post detection event parameters e Automatic Gain Control AGC o 10 20 or 30dB maximum gain settings Each stage of processing can be enabled disabled and custom configured even as the AUDIOPHILE unit continues to operate on the incoming audio signal Descriptions of each filter type its application and a definition of the control parameters can be found in Chapters 5 19 1 2 Installation To install the AUDIOPHILE software simply insert the AUDIOPHILE Installation CD into your CD ROM drive If the installation software does not automatically run after several seconds you will need to manually start the installation as follows With the AUDIOPHILE Installation CD in your CD ROM drive click on the Start menu and then the Run option In the window that appears type X setup exe And click OK or hit the Enter key Where X is the drive letter of your CD ROM Th
32. ion of the Broadband Stage is governed by a single control the Amount slider control Adjusting the Amount allows the user to precisely control how much noise reduction is being applied the greater the value the more aggressive the operation of the Broadband Stage Because large amounts of noise reduction invariably create audible birdy noise artifacts in the output audio due to the nature of adaptive frequency domain processing the user should always try to minimize the amount of noise reduction being applied to achieve the best balance between maximal noise reduction and minimal audible artifacts The controls for the Broadband Stage are described in Chapter 2 4 15 0 20 BAND GRAPHIC EOUALIZER Application The 20 band Graphic Equalizer is an easy to use linear phase FIR digital filter that is used to reshape the spectrum of the final output signal Reshaping is accomplished with twenty vertical scroll bars also called slider controls which adjust the attenuation of each frequency band These controls are very similar to the slider controls found on analog graphic equalizers found on many consumer stereo systems and thus should be very familiar to even the novice user However unlike analog graphic equalizers this digital equalizer has some very powerful additional capabilities For example the Normalize button allows the user to instantly move all slider controls up until the top slider is at OdB The Zero All button instan
33. ization MUST occur to maintain consistency between what is displayed in the interface and what is currently running on the unit The user has two choices either the software will push down to the hardware its current settings and thereby changing what is currently running on the unit OR the software will retrieve the current settings directly from the hardware and update its interface accordingly and leave the hardware essentially unchanged It is important to remember that regardless of which option is selected after the synchronization occurs the PC software will now be in control and any changes made will be sent down to the hardware unit This option can be accessed in the Hardware menu If the user wishes for the software to retrieve the settings from the hardware the Synchronize To Hardware On Connect should be checked This setting will be remembered between software restarts NOTE upon Disconnect the hardware will always perform a reset and reload whatever is stored in its flash memory even if no changes were made to the configuration This may have the unintended side effect of resetting any adaptive filters 3 0 STORING FILTER CONFIGURATIONS 3 1 Save File Dialog Box Application To save time configuring the AUDIOPHILE control settings complete setups may easily be stored to disk setup files for future recall Store a setup to a disk file as follows 1 Click on File on the AUDIOPHILE menu bar When the pull down m
34. r stable tones and reverberations Larger adapt rates sometimes affect voice quality as the filter may attack sustained vowel sounds When selected the specified Adapt Rate is continuously rescaled depending upon the input signal level This makes the filter convergence rate consistent regardless of the audio level being applied to the input When not selected the specified Adapt Rate Mu is applied to the filter at all times Overall convergence rate tends to be faster and more consistent when the Auto Normalize feature is selected Sets the number of samples in the prediction span delay line Prediction span is indicated both in samples and in milliseconds and can be adjusted from 1 to 64 samples Shorter prediction spans allow maximum noise removal while longer prediction spans preserve voice naturalness and quality A prediction span of 2 or 3 samples is normally recommended Used to select the output of the filter The Normal setting allows the audio remaining after predictable noises have been subtracted to be output The Rejected setting allows the predicted noises to be output effectively allowing you to hear what the filter is removing Used to clear the adaptive filter coefficients and cause the filter solution to rebuild from scratch 6 0 LOWPASS FILTER Application The Lowpass filter is used to decrease the energy level lower the volume of all signal freguencies above a specified Cutoff Freguency thus reducing hi
35. r drawing window described in Chapter 16 Edit Custom Curve WE HHHH HHHHHHHHHHHH HHHEHHHH HHHHHHH HHHHHHH HHHHHHH HHHHHHH yr ar ar urat t HHH HHH HHH HHH HHH wy adm Figure 17 2 ASIF custom curve drawing window Filter Output The controls in this block allow the user to make adjustments to the filter output The filter amount setting controls the degree to which the ASIF can affect the signal with 0 corresponding to no filtering and 10096 corresponding to full filtering In general it is best to use the minimum Filter Amount setting that produces the desired result Also there are two options for adjusting the level of the final ASIF output When Auto Gain is enabled the ASIF automatically monitors the input and output levels and applies a gain value that matches the output level to the input level When Auto Gain is disabled the user can use the gain slider control to precisely specify the amount of boost applied to the ASIF output The Auto Gain is an adaptive value whose rate of change depends on the same Adapt Rate slider setting that controls filter coefficient averaging This means that when the filter response changes rapidly and dramatically the auto gain will take some time to catch up to these changes In particular the output audio may clip when user settings are changed in a ways that have a boosting effect such as switching from a pink to a flat shaping curve adjusting the filter amount
36. resent In these situations set the Notch Harmonics option to either Odd or Even Comb Configuration Comb Frequency Notch Limit T TE Lond Harmonics Notch Depth E Er Even E Enable O Odd J Figure 10 1 Comb Filter Control Window Description of controls is as follows Comb Specifies fundamental frequency in Hertz of comb filter Frequency Notches are generated at multiples or harmonics of this frequency Notch Limit Specifies frequency in Hertz above which no notches are generated Minimum Notch Limit is 2 times the Fundamental Notch Frequency while maximum Notch Limit is 8800 Hz Notch Limit is adjustable in 1 Hz steps Notch Depth Depth of notches that are generated Notch Depth is adjustable from O dB to 120 dB in 1 dB steps Harmonics Specifies whether notches will be generated at All Odd or Even multiples or harmonics of the Comb Frequency If for example the Comb Frequency is set to 60 000 Hz then selecting All will generate notches at 60 Hz 120 Hz 180 Hz 240 Hz 300 Hz etc Selecting Odd will generate notches at 60 Hz 180 Hz 300 Hz etc Selecting Even will generate notches at 120 Hz 240 Hz 360 Hz etc TIP A comb filter is adjusted in the following manner Set the Notch Limit and Notch Depth to their maximum positions set Harmonics to All Next adjust the Comb Frequency to achieve maximum hum removal normally this will be in the vicinity of 60 or 50 Hz Analog recordings will seldom be
37. s up one at a time to hear only what you wish to hear 16 0 HI RES GRAPHIC EQUALIZER Application In some applications it may be necessary to precisely reshape the spectrum of input audio prior to passing it through successive DSP filter stages For example if the audio is from a microphone which has an unusual frequency response curve for example a microphone acoustically modified as a result of concealment a compensation filter that reshapes the audio to a normal spectral shape might be desirable The Hi Res Graphic Equalizer is essentially a 115 band graphic equalizer however instead of having 115 separate slider controls it allows the user to precisely draw the desired filter shape on the computer screen using the mouse with as much or as little detail as desired Simply click and drag the EQ points or handles as desired To eliminate an EQ handle simply right click it As the filter shape is drawn a linear phase digital FIR filter is constructed in the PC and transferred to the AUDIOPHILE unit for implementation The Normalize button allows the user to shift the entire filter curve up until the highest point is at OdB Hi Res Graphic Configuration Enable Normalize 100 0 dB HH oe Left click to add a handle wy hy X wv Right click on a handle 60 2 28 SF OSO SSS SS ER S e lo delete it Click and drag handles to adjust attenuation Figure 16 1 Spectral Graphic Equalizer Window Description o
38. s used to decrease the energy level lower the volume of all signal freguencies above a specified Lower Cutoff Freguency and below a specified Upper Cutoff Frequency The signal region between the Lower Cutoff Frequency and the Upper Cutoff Frequency is called the stopband region The Bandstop filter is useful for removing in band noise from the input signal The Lower Cutoff Frequency is usually set below the frequency range of the noise while the Upper Cutoff Frequency is set above the frequency range of the noise While listening to the filter output audio the Lower and Upper Cutoff Frequencies can be incrementally adjusted to achieve maximum elimination of noise while minimizing loss of voice The amount of volume reduction in the stopband region can further be controlled by adjusting the Stopband Attenuation setting maximum volume reduction is 120dB The slope at which the volume is reduced from normal at each Cutoff Frequency to the minimum volume specified by Stopband Attenuation can also be controlled by adjusting the Transition Slope setting Bandstop Configuration Lower Cutoff Frequency Upper Cutoff Frequency Transistion Slope Stopband Attenuation Enable Figure 9 1 Bandstop Filter Control Window Description of controls is as follows Lower Cutoff Specifies frequency in Hertz below which no signals are Frequency attenuated Frequencies between this cutoff and the Upper Cutoff Frequency are attenuated Minimum Lower
39. signal levels are at or above the 18dBFS reference level the AGC will have no effect Maximum Gain specifies how much gain the AGC can apply in its attempt to bring the output signal up to the proper level The greater the Maximum Gain the lower the output signal level that can be brought up to proper level The Maximum Gain options are OdB Bypass 10dB 20dB and 30dB For most near party far party applications the 10dB setting is recommended Maximum Gain settings greater than 10dB may elevate background noise excessively during pauses in speech A soft AGC using 10dB is often useful even when large voice level differences are not present For the AUDIOPHILE product the AGC implementation incorporates a special look ahead feature which allows the algorithm to anticipate large signal transients and begin reducing the applied gain prior to their occurrence This minimizes the potential for short term clipping distortion on the output whenever the audio transitions from low signal level and high gain applied to high signal level where a low gain needs to be applied The look ahead feature also has benefit in the opposite case the gain is able to begin increasing prior to a transition from loud audio e g near party to low level audio e g far party allowing the initial portion of the far party audio to be more audible than it would ordinarily Controls for the AGC algorithm are described in Chapter 2 7
40. ss filter and its controls is shown below Attenuation dE Transition Slope dB Octave Stopband Attenuation Transition Passband Stopband Bund and Cutoff Frequency Hz Frequency i Figure 7 2 Highpass Filter Graphical Description 8 0 BANDPASS FILTER Application The Bandpass filter is used to decrease the energy level lower the volume of all signal frequencies below a specified Lower Cutoff Frequency and above a specified Upper Cutoff Frequency thus combining the functions of a seriesed Lowpass and Highpass filter into a single filter The signal region between the Lower Cutoff Frequency and the Upper Cutoff Frequency is called the passband region The Bandpass filter is useful for simultaneously reducing both low frequency rumble and high frequency hiss The Lower Cutoff Frequency is usually set below the voice frequency range somewhere below 300 Hz so that the voice signal will not be disturbed While listening to the filter output audio the Lower Cutoff Frequency minimum of 0 Hz can be incrementally increased until the quality of the voice just begins to be affected achieving maximum elimination of low frequency noise The Upper Cutoff Frequency is usually set above the voice frequency range somewhere above 3000 HZ so that the voice signal will not be disturbed While listening to the filter output audio the Upper Cutoff Frequency minimum setting of 100Hz over the Lo
41. sting the Slot Frequency up or down 1 Hz at a time while listening to the Slot filter output on the headphones Usually the signal frequency will not remain constant but will vary slightly due to modulation recorder wow and flutter and acoustic beating Therefore you may need to increase the Slot Width from its minimum setting to avoid having the signal move in and out of the slot Slot Configuration Slot Frequency Stopband Attenuation J J Slot width Enable Figure 12 1 Slot Filter Control Window To optimize background noise reduction for your application set the Stopband Attenuation to 120dB If however you wish to leave a small amount of the background noise mixed in with the isolated signal adjust the Stopband Attenuation to the desired value Description of controls is as follows Slot Freguency Specifies frequency in Hertz which is to be enhanced in the input audio Minimum Slot Frequency is O Hz while maximum Slot Frequency is 8800 Hz Slot Frequency is adjustable in 1 Hz steps Stopband Specifies amount in dB by which frequencies other than the Slot Attenuation Frequency are attenuated Stopband attenuation is adjustable from OdB to 120dB in 1 dB steps Slot Width Width of the generated slot in Hertz Adjustment range is 33 1 Hz to 3845 2 Hz A graphical description of the Slot filter and its controls follows in the figure below Note that the slot width is defined at its 6 dB points Attenuation
42. ted to stop the installation because these drivers may harm your system These drivers will not harm your system click Continue Anyway Hardware Installation The software you are installina for this hardware Audiophile Hardware has not passed Windows Logo testing to verify its compatibility with Windows lt P Tell me why this testing is important Continuing your installation of this software may impair or destabilize the correct operation of your system either immediately or in the future Microsoft strongly recommends that you stop this installation now and contact the hardware vendor for software that has passed Windows Logo testing Continue Anyway Step 9 Click Finish Found New Hardware Wizard Completing the Found New Hardware Wizard The wizard has finished installing the software for e Audiophile Hardware Click Finish to close the wizard CAY Page 11 You can now run the Audiophile software by clicking on the Audiophile icon located on your desktop or under your Start menu 2 0 AUDIOPHILE CONFIGURATION CONTROL 2 1 AUDIOPHILE Command Center Audiophile Command Center File Hardware Help z E Filter 1 Broadband Stage VOX 1 CH Adaptive Amount 682 Detection Threshold 7 dB default J Pre event time 1 sec v Enable Post event time 5 secs Y Enable O Silence CTone v Enable O Speech Activity Filter 2 Equalizer Stage AGC Maximum Gain Bandpass v Adaptive S
43. then disappear This is normal It is registering the drivers with the operating system that will be used to communicate to the Audiophile hardware Step 5 At this point you should see an Audiophile Command Center icon on your desktop Turn on your Audiophile hardware and connect it to the PC using the supplied USB cable Step 6 When Windows is notified of the new hardware you will see the Found New Hardware Wizard appear Select No not this time to tell Windows not to try to download a driver from the Windows Update Service Click Next Found New Hardware Wizard welcome to the Found New Hardware Wizard Windows will search for current and updated software by looking on your computer on the hardware installation CD or on the Windows Update Web site with your permission Can Windows connect to Windows Update to search for software O Yes this time only O Yes now and every time connect a device O No not this time Click Next to continue Cancel This wizard helps you install software for Audiophile Hardware If your hardware came with an installation CD EP or floppy disk insert it now What do you want the wizard to do eir O Install from a list or specific location Advanced Click Next to continue CAN Page 10 Step 8 The operating system will find the drivers that were registered in Step 4 These drivers are not signed and if you are using Windows XP you may be promp
44. tly sets all the sliders to OdB The Reduce All 1dB button instantly moves all sliders down by 1dB The Maximize All button instantly sets all sliders to maximum attenuation None of these functions is available in an analog graphic equalizer Notice also that the 20 sliders are spread across the available system bandwidth and that the frequency spacing is optimized for voice processing vs general music EQ as on most commercially available equalizers Graphic EQ Configuration 21dB 6dB 1dB dB dB dB 4dB 7dB 10dB 15dB 18dB 19dB 21dB 26dB 29dB 39dB 48dB 61dB 83dB Zero All EI SN C e l Reduce All 1dB Maximize All C LUSIT AE HE US TET MAR SG Tf A DO ET IET ELT I C C EDE DODE EO OD D MR ME NN EE Y AN AIN C EV E TE N TE CE N N ED C E OER AAA c1 ME TSS OE N OE Wier GET OUO EDU Fine CR OO TEE DEL GEE TR DLE LE UR AO OA A UA AAA MU IN EN IA AA OO DAL LA OG OE Mt DE A OS EOS AAA UA dd E UR OO RO erate 0 COO CeCe Le Ee ETE f V Ret TT TET O0 FE AT Te D UR UT V DE A E E DIOE GET OE OER TOT ESEPTA OE IE AAA KA LE EI 110 330 550 770 990 12K 14K 17K 19K 21K 24K 30K 35K 42K 48K 55K 62K 68K 75K 81k M Enable Frequency Hz Figure 15 1 20 Band Graphic Equalizer Control Window Description of controls indicators is as follows Slider controls The twenty vertical scroll bar slider controls are used to set the frequency response of the equalizer Each slider can set the
45. to identify the frequency of the noise this is best done using a Spectrum Analyze Initially set the Notch Depth to 120 dB and the Notch Width to the narrowest possible value Next set the Notch Frequency to the noise frequency Fine adjustment of the Notch Frequency may be necessary to place the notch precisely on top of the noise signal and achieve maximum reduction of the noise This is best done by adjusting the Notch Frequency up or down 1 Hz at a time while listening to the Notch filter output on the headphones Often the noise frequency will not remain absolutely constant but will vary slightly due to modulation recorder wow and flutter and acoustic beating Therefore you may need to increase the Notch Width from its minimum setting to keep the noise within the notch For maximum noise reduction set the Notch Depth to 120dB It is best to adjust the Notch Depth up from 120 dB until the tone is observed then increase the depth 5 dB Notch Configuration Notch Frequency Notch Depth Notch Width Enable Figure 11 1 Notch Filter Control Window Description of controls is as follows Notch Freguency Specifies freguency in Hertz which is to be removed from the input audio Minimum Notch Frequency is O Hz while maximum Notch Frequency is 8800 Hz Notch Frequency is adjustable in 1 Hz steps Notch Depth Depth of the notch that is generated Notch Depth is adjustable from O dB to 120 dB in 1 dB steps Notch Width W
46. ut signal The length of this adaptation period depends on the Adapt Rate control setting This control allows the user to select the rate of adaptation for the spectral average on which the ASIF response is based The spectral averager uses an exponential average of the form Hi a Xi 1 1 a Hi The value shown in the display box corresponds to the averaging constant a in the exponential average The lower the adapt rate value the slower the filter will respond to changes in the input audio Note Fast response sounds like a good thing so it can be tempting to set the adapt rate to a high value However the goal Output Shape Custom Curve of the ASIF is not to remove transient noises but rather to reshape the long term spectral envelope of the signal If the adapt rate is too fast the filter will respond too quickly to transient audio characteristics which will produce artifacts in the output audio and will prevent the filter from settling on a good average solution For this reason most applications will work best with adapt rates at the low end of the available range f you hear tonal artifacts that come and go in the output audio or if the filter trace display coefficients seem to be changing rapidly you probably need to reduce the adapt rate In this block the user can select the target spectral shape that the filter attempts to achieve The ASIF has an inherent spectral flattening effect on the audio The s
47. wer Cutoff Frequency can be incrementally lowered until the quality of the voice just begins to be affected achieving maximum elimination of high frequency noise The amount of volume reduction outside the passband region can further be controlled by adjusting the Stopband Attenuation setting maximum volume reduction is 120dB The slope at which the volume is reduced from normal at each Cutoff Frequency to the minimum volume specified by Stopband Attenuation can also be controlled by adjusting the Transition Slope setting Bandpass Configuration Lower Cutoff Frequency Upper Cutoff Frequency J mr ee LO Transistion Slope Stopband Attenuation Enable Figure 8 1 Bandpass Filter Control Window Description of controls is as follows Lower Cutoff Specifies frequency in Hertz below which all signals are Frequency attenuated Frequencies between this cutoff and the Upper Cutoff Frequency are unaffected Minimum Lower Cutoff Frequency is O Hz while the maximum Lower Cutoff Frequency is 10 Hz below the Upper Cutoff Frequency Lower Cutoff Frequency can be adjusted in 1 Hz steps NOTE The Lower Cutoff Frequency can never be set higher than 10 Hz below the Upper Cutoff Frequency Upper Cutoff Specifies frequency in Hertz above which all signals are Frequency attenuated Frequencies between this cutoff and the Lower Cutoff Frequency are unaffected Minimum Upper Cutoff Frequency is 10 Hz above the Lower Cutoff Frequency wh
Download Pdf Manuals
Related Search