MUS 510 / CSC 510
DIGITAL AUDIO TECHNIQUES

Text from now-defunct Syntrillium Cool Edit Pro Tutorials
(adapted re Audition)

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Contents:  A Short Course in Digital Audio, plus:  1. Recording Set-Up & Basics, 2. Device Order, 3. Edit View, 4. Multitrack Sessions, 5. Multitrack View, 6. Multitrack Recording, 7. Noise Reduction, 8. Splitting Tracks

Highlights from:  A Short Course in Digital Audio

Sound is created by VIBRATIONS, such as with a guitar string, vocal cords, etc.  The vibrations disturb the air molecules causing motion, and slight changes in air pressure.  When these pressure waves reach us, they vibrate the receptors in our ears.  We hear the vibrations as sound.  When you see a graphic of an audio waveform, that waveform represents these pressure waves.  The amplitude of the waveform the measurement from the peak of the waveform to the trough.  A cycle is amount of time it takes the waveform to complete one cycle of amplitude changes, returning to the same point.  The frequency of the waveform is how many cycles it goes through each second.  For example, A440 = 440 vibrations per second.  

A MICROPHONE works by changing the pressure waves of sound into changes in voltage on a wire.  These changes in voltage match the pressure waves of the original sound.  High pressure = high voltage.  Low pressure = low voltage.  Voltages transfer down the wire and can be recorded onto tape, for example, as changes in magnetic strength.  On vinyl, the voltages would transfer to changes in the amplitude in the grooves.  A SPEAKER works like a microphone in reverse.  The speakers vibrate to recreate the pressure waves.  The above is referred to as analog audio.

In digital technology, waveforms are broken up into individual samples in a process called sampling (analog to digital conversion).  The sampling rate defines how often a sample is taken.  (See Sampling Rate under Terms.  Also, see Nyquist Theorem, Bit Resolution, MIDI.)  

1. Recording Set-Up & Basics (WERecord.exe)

Before Audition can record, Windows must be configured to use the proper sound device.  Recording is done using a sound card’s line-in, mic port, and more. This tutorial will show how to set a standard Windows sound card to record into Audition.  If you have a specialized card, some information may not apply; check your card’s documentation. 

First, make sure the recording device is plugged into the computer’s sound card and note the label on the port it is plugged into.  Then, start Audition.  Within Audition, there is a shortcut to the Windows Recording Controls.  Go to Options > Windows Recording Mixer.  Find the port the device is plugged into, and select it, or if there is a “mute” choice, mute all except the desired port.  For example, if the device is a microphone, make sure that it is plugged into the microphone port, and choose microphone as the recording device.  These settings will take effect under Windows. 

Next, go to Options > Device Order, and click on the “Recording Device” tab.  There are two lists, and one of them will show your sound card.  If you are not sure which sound card you have, consult your computer’s documentation.  When you find your sound card, click on it, move it to the right side, to the “Multitrack Device Preference Order” column, and then click “Use in EV.”  Then click “Move Up” until it is first, and then go “OK.”  The EV tag means that this is the device to be used in the Edit View.  Then, go to Options > Settings and then select the General tab.  Check “Live Update During Recording” and “Auto-Scroll during playback and recording” if you want to see your waveform as you record.  Now go to the Edit view, which is the single stereo track editor.  To toggle between Edit and Multitrack views, use the F12 key, or check the View menu.  Click on File > New, and select the sample rate and depth.  Generally, it is best to leave it on 44,100 stereo, 16 bit, which is CD quality sound.  When ready, click on the red, “Record” button in the lower-left hand corner.  When clicked, Audition starts recording.  Click the “Stop” button when finished. 

 

2. Device Order (DevOrder.exe)

Proper setup of devices is critical in Audition.  This tutorial covers device ordering, and specific device settings that are controlled by Audition.  There are also other settings such as Volume that are controlled through either the Windows mixer or a proprietary mixer, so be sure to familiarize yourself with those settings as well. 

Start by clicking Options >Device Order.  This brings up the Device Ordering Preferences. Under all four tabs, the premise is the same:  The left side “Unused Playback Devices” lists all the devices that Windows believes are soundcards, and are NOT used in Audition.  The right side is a list of all the devices Windows believes are soundcards, and ARE available in Audition.  The order that Audition uses the devices in is determined by the ordering of the devices on the right side list.  Move the devices back and forth to use or not use them.  Move the devices up and down in the right column to set their order.  The way that the device order is set will determine how the devices are numerically listed in the multitrack. 

The Playback and Recording tabs have two more features:  First you need to determine which device should be used in the Edit View for single track editing.  Select a device by clicking on it, and then click the “Use in EV” button.  This device will now be the device used in the Edit View.  Do this for both Playback and Recording.  Second, as long as one sound card is installed, there will be another device listed called “Wave Mapper.”  It is a virtual device – simply, Wave Mapper is the default windows sound device.  If you have Wave Mapper selected, the device will only change when the windows default device is changed in the Windows Control Panel.  It is usually best to select the appropriate sound card, and not use the Wave Mapper unless necessary.  Under the two MIDI tabs, this default virtual device is called MIDI Mapper, and works the same way. 

Once the order for all of the desired devices has been set, then make sure the properties of the individual cards are set appropriately.  Click on the device and then Properties, or in the main Audition window click Options > Device Properties.  Then select the appropriate device.  The Wave Out tab has four areas.  Limit Playback to” is helpful if the sound card being used can only playback audio at a limited bit depth.  Send 32-bit as” gives the option to change how your sound card plays back 32-bit audio.  The default settings are fine for most sound cards, however this can be changed if you are having specific problems playing 32-bit audio.  Enable Dithering gives you a choice of using dithering on the playback signal.  This is useful when playing back higher bit resolution files at a lower bit rate.  For example, if an audio file is 24- or 32-bit and your sound card is only capable of playing back at 16-bit resolution, enabling dithering in this case would result in better audio playback quality.  The “Supported formats” grid shows what playback rates are available for that card.  The Wave In tab has three areas.  The “32-bit playback” is a 32-bit option for recording.  The default setting is usually correct for most sound cards, but this is where you can change the setting for how 32-bit audio is recorded if needed.  Multitrack latency” is a setting that can be adjusted based on your sound card’s performance.  Some cards introduce a certain amount of latency that can be balanced with this setting.  See the Manual or the help file for detailed information.  The “Supported formats” grid shows what recording rates are available for the card. The MIDI Out tab shows the MIDI Out device as well as where any SMPTE signal would be routed.  The MIDI In tab confirms any MIDI In device change and shows where Audition will look for a SMPTE signal to slave to.  The External Controller tab refers to supported external controllers, such as the Syntrillium Red Rover.

Once your devices are set properly, Audition will be able to use them properly.

 

3. Edit View (WEInterf.exe)

Audition is designed to be an intuitive program, so you will find tools and functions grouped together.  This tutorial is designed to give a quick overview of the basics within the Edit View, which is the single stereo track editor.

First, make sure that you are in Edit View.  There are two main views – Edit and Multitrack.  Switch between them by clicking the toggle button in the upper-left corner, or pressing [F12].  Edit View will have a large blank work area.  

Open a sound file by selecting File > Open.  The waveform appears, and now we can control it using the transport controls.  There are many common choices such as:

  • Stop
  • Play
  • Pause

The play button with a circle is Play to End – click it to play to the end even if you are zoomed in so all the audio isn’t visible.  Right click on the Play, and Play to End buttons to change the behavior.  Play Looped is the infinity sign. 

Go To Previous and Go To Next cue points, or the beginning or end, Fast Forward, Rewind and Record. To place the cursor, simply click once on the audio waveform.  You will see that when one point is selected, a dotted line marks the location.  If you want to select a range, click and drag from start to the finish of an area, and release the mouse button.  A range is noted by a selection of the audio becoming a different color, and allows for editing just the selected area.  To change the highlighted areas, drag the handles from above or below.  For precision, enter the exact times in the selection/view window. 

These [magnifying glasses] are the Zoom buttons.  Use the zoom buttons to zoom in and out of the waveform for precise editing.  Leave your pointer on top of any button for a few seconds and a pop-up will tell you what that button’s function is. 

On the left is the organizer window.  If the window is not displayed, go to View > Show Organizer Window.  This shows three types of items:

  • Currently opened files – double click on the file name to switch to it.
  • Available effects – quickly see what is available for your file.
  • Favorites – a customizable list of favorite effects, scripts and tools. 

The level meters, or “VU” meters, are available on the button of the screen.  This window can move, resize, and dock anywhere.  Also, right clicking on the meter makes adjustments to ranges, peaks, and indicators.

These controls are the basis for everything you do in Audition.  Mastering these controls makes editing quick and easy. 

 

4. Multitrack Sessions (MTSess.exe)

Audition creates sessions in the multitrack view.  This tutorial will define the parts of a session, and describe how they work together. 

 Create a new, empty session by going to File > Session.  Select a sample rate:  44,100 is the default for CD quality.  Now open a few audio files, like waves, mp3s, or loop files.  The Organizer window shows all the files that are opened.  Drag and drop these files into the session tracks.  This is already a session!  A session consists of audio files and a .SES (“SessionName.ses”) file, known as a “session file.”  A session file is like a map.  It contains no audio, but it holds information about where audio blocks are positioned in the multitrack view, track specific information such as volume and effects settings, session-specific settings and options, and device preferences.  Also, the session file knows where the audio files are located on the hard drive. If an audio file is moved before a session is reopened, Audition will prompt you to find the original file. 

 The easiest way to save a session so that it’s portable is to save the session file and all of the associated files into a new folder.  Go to File > Save Session As.  Change the Save in list box to your desired location, such as Desktop.  Then click on Create New Folder and name the new folder.  Double click on the folder to open it.  The Save in list box should now say the name of the new folder.  Next, add a checkmark to the Save Copies of All Associated Files, and then click on the Options button.  To change formats of the audio, check the Save All Copies in This Format box, and choose the appropriate format – usually Windows PCM wav.  Using compressed audio formats, such as mp3 or wma files, can cause file lengths to change so use Windows PCM or Audition Loop / CEL files.  CEL files are compressed using mp3PRO technology, but do not extend file time lengths.  Now that you have saved the session and all of its associated files to a single folder, the session is now portable.  Just remove the whole folder to move the session to another hard drive, computer, or disc.  At any point during the session, you can create a stereo file that is a complete mix of the whole session.  Select Edit > Mix down to file > all waves.  Audition will create a mixdown, and then switch into the Edit view to show the new file.  The new file is listed in the Organizer window, and is appropriately called Mixdown – the temporary name for this file.  It is a file of exactly what was heard in the multitrack, all mixed into one stereo file.  This newly created wav file can then be saved as a file, and burned to an audio CD.

 

5. Multitrack View (MTInterf.exe)

Audition is a very powerful multitrack editor.  This tutorial is intended to give an overview of the Multitrack View.  A complete list of features and how to use them is available in the Audition manual. 

Remember, right clicking on most objects will bring up a context menu with choices of what can be done with that object. The Organizer Window has three components.  First, waves that are open in Audition are listed under files.  Drag and drop a file from the organizer into a track to add it to the mix. Click the Effects tab to see an organized tree view of available real-time effects for Audition. Click and drag an effect on to a track to add it as a real-time effect for that track. 

The Favorites tab lists favorites defined in the Edit View.  Only tool-type favorites are available in the Multitrack View, so some favorites will not be available.  The default multitrack view shows 4 tracks, though there are 128 stereo tracks available.  To show more or fewer tracks, use Zoom In or Out Vertically.  Scroll through the tracks by dragging the right hand ruler up and down.  Also, you can zoom to a specific number of tracks by right clicking and dragging on the right hand ruler. The Transport, Zoom, and Selection controls are the same as in Edit View.  Each block can be selected simply by clicking on it.  Select multiple blocks by holding the control key, and clicking on the blocks.  Once a block has been selected, then it can be moved.  Right click and drag to move a block left and right.  Right click and drag up and down to change tracks.  Again, select multiple blocks by control clicking, and right click and drag them to move in tandem.  A move can be reset using the Undo button.  Each of the tracks has its own set of properties.  The track controls on the left display settings and controls for each track to view all properties, right click the controls. 

Toolbars give quick access to shortcut buttons directly in Audition.  Find out what each button does by leaving the pointer on top of the button.  A tool tip will appear stating what the button does.  To adjust the toolbar preferences, go to View > Toolbars. 

These features are the basics for the Multitrack environment.  Mastering these concepts will make working in Audition fast and easy.  Be sure to watch the “Multitrack Session Basics” tutorial to become familiar with how audio files work in tandem with Windows and Audition. 

 

6. Multitrack Recording (MTRecord.exe)

Multitrack recording has a few more variables than recording in Edit View, such as track and device selection.  This tutorial will show how to directly record onto the multitrack. 

Before you begin, make sure that all of the device inputs are configured correctly in Audition’s Device Order.  Go to Options > Device Order, and click on the Recording tab in view all the inputs.  Any device that Audition will be able to use must be listed in the Multitrack Device Preference Order column.  Set the primary input as first in this list, and below it, any other inputs that may be used to record as well.  Any device in the Unused column will not be available for recording.  Click OK when done to accept any changes. 

Now that the devices are properly configured, select a track to record into.  Audition can record from multiple sound cards and inputs at the same time, so be sure to select the appropriate device to use.  Right click in a blank area of the track controls.  This will bring up the Track Properties for the selected track.  These are all the possible settings for an individual track.  This is also where the track name can be changed to a friendly name. Select the desired output device, desired input source, whether you want mono-left, mono-right, or stereo recording, and the bit depth.  The sliders for volume and panning effect a track after it has been recorded in.  Record, Solo, and Mute buttons are available in the track properties.  Click on the record button.  Now close the Track Properties window.  Notice that the track controls now show the “R” button depressed.  This indicates that the track is armed for recording.  In fact, changing most of the track properties can be done by using the track control area to the left of each track.  To adjust the volume or panning, click over the box and drag up and down.  To begin recording, position the cursor at the desired point on the timeline.  Then simply click on the master recording button in the transport control, and Audition records.  Click stop to end the recording.  When finished, a waveform block in the track now exists.  This waveform block can now be edited, moved or modified as desired. 

 

7. Noise Reduction (NoiseRedux.exe)

The noise reduction feature in Audition is very powerful and does and excellent job at removing specific audio noise and unwanted hums, hisses, and other sounds in an audio file.  This tutorial covers how to use Audition’s noise reduction feature, which is found under Effects > Noise Reduction > Noise Reduction.  More specific information on settings and what they do can be found in the Audition manual.

First find an area of your file that contains only audio that you want to remove, get at least two seconds of the noises if possible, if not get as much as you can.  This is important; the noise reducer builds a profile based on this sample.  Highlight the noise, then go to Effects > Noise Reduction > Noise Reduction.  Then click on Get Profile from Selection.  The noise profile will fill in with the graph showing sound at their different frequencies.  Next, click Close in the Noise Reduction dialogue--DON'T click OK.  Now that you have a noise print, you need to select the audio you want to run the reduction on.  Usually that’s the entire file.  If that is the case, double click anywhere any where in the waveform to selection everything in the current view.  Once you have made your selection, go back to Effects > Noise Reduction > Noise Reduction.  You can also press F2 which is a shortcut which brings up the last function.  Click OK to run the noise reduction on the file.  Now listen to your audio and see if it is an acceptable result.  If not, undo the reduction and start again.  You may be able to adjust the settings and achieve a better result.  Try using the preview button to hear the selection with the reduction and click the Bypass check box to hear it without the reduction.  If you hear a warbled, watery, or metallic sound, try reducing the noise reduction level.  If the problem remains, acquire a new sample for the profile and make sure that the sample contains only noise.  If you are removing the same noise from multiple files, use Save Profile to keep the same profile and apply it to future noise reductions. 

There is more information in the Audition Help file and manual regarding specific settings and definitions for each of the settings.  Refer to the manual for additional tips, trick, and information on how to get the most out of the noise reduction function. 

 

8. Splitting Tracks (tracksplit.exe)

One of the most common tasks with digital audio is to get that audio onto a CD.  This requires preparing your audio in a very specific way.  This tutorial will walk through the steps in preparing your audio including how to prevent gaps and clicking noises between tracks. 

We’ll start with some background information.  CDs store information in chunks of data called Frames.  Frames hold exactly 588 audio samples and there are 75 frames for each second of CD audio, creating a sample rate of 44,100 samples per second.  If you do not edit your audio exactly on these frame boundaries the CD burning software will complete any partial frames with blank data.  This may add unwanted silence or clicking to your burned CD. 

First make sure your audio is in the necessary format.  In the status bar at the bottom right you should see the status listed as 44,100 16-bit stereo.  If it does not, go to Edit > Convert Sample Type and select 44,100 16-bit stereo.  Now that you have the audio in the correct format, you can cut it into tracks.  You need to make sure that any cuts are made between frames.  To do this, change the timeline units to CD frames.  Right click on the Timeline and select Time Frame Format and then select Compact Disc 75fps.  Now the ruler and time display will display time in CD frames.  Right click on the Timeline again and select Snapping > Snap to Cues always.  Anytime you click on the waveform the cursor will now snap to an exact frame boundary. 

Now you are ready to cut the track into tracks.  Since Audition is set up properly to 75 frames per second and to snap to frames, any edit you make should work properly with your CD burning software.  Place the cursor where you want to cut the file and press F8 to drop a cue mark.  Continue to add cues to the audio until it is split into tracks the way you want.  Next add a cue at the very beginning and at the very end of your file.  Now go to View > Show Cue List.  The cues in the list are labeled Cue 1 to Cue X depending on how many you created, and they only have a beginning time listed.  You need to change these cues from cue points to cue ranges so that they each define a track length.  Select all of the cues by pressing control and clicking on each one and then click Merge.  This will convert all of your cues from points to ranges. 

You are now ready to save these cue ranges as separate files to burn to a CD as tracks. Click on the Batch button and select Save to Files.  This will bring up several options.  If you have named the cues, check Use Cue Label as file name prefix to keep the cue name as the file name prefix when saved.  For now I’ll leave that unchecked and use the word Jazz as my prefix.  Now click on Browse under destination Destination Folder.  It is recommended that you create a new folder to save all of tracks in.  Do this by navigating to the folder you save your audio in and clicking the New Folder button and OK.  For output format select Windows PCM wav.  Click OK and Audition starts the batch process.  Audition will save each cue range as a new file in the directory you created.  And in this example they will be Jazz 01, Jazz 02 and so forth.  These files are ready to burn.  Take these files to your burning software and add them to your CD layout.  Be sure to use “Disc at Once Burning.”  The other option is “Track at Once” which will add two seconds of silence between each of the tracks.  Finally begin the burning process and enjoy your CD.

 

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