Objectives

• Learn how to manipulate music and sound in a desktop audio editing environment.
• Experiment with various editing techniques for digital audio including copy, paste, and cropping; fade in and fade out; amplitude and envelope alterations; reverb and echo; and others.
• Record digital audio from a live or prerecorded source.
• Add additional tracks to a digital audio clip.
• Learn how to convert a variety of digital audio file types.

Directions

1. Read through the hands-on tutorial to gain an overview of the process
2. Follow the hands-on tutorial, step-by-step, to experiment with various prerecorded music and sound clips
3. Digitally record some live music and/or sound on your own
4. Use the Worksheet for Project 15 (see below) to record your work.
5. Submit the completed Worksheet with the Evaluation Form for Viewport VII

Software

• The Worksheet for Project 15 is an Adobe Acrobat file. From the Acrobat reader you can print out copies of the form.

 
• Click here to view the Worksheet directly from those Web browsers that will automatically display Acrobat files (e.g., Netscape, Microsoft Internet Explorer, NCSA Mosaic browsers).

 
• For those Web browsers that will not display Acrobat files (e.g., HTML Viewer) download the Project 4 Worksheet to your hard disk. Then drag the file onto the icon of the Acrobat reader application.


• Peak LE version 1.63. You will need a digital audio software package like Peak LE from Bias. The project below is tailored to Peak LE. We suggest you use the most recent version if possible.

 
• Guidesheet files. A folder of files especially prepared for Project 15 is available on the EMT CD-ROM disk. You will need these to complete the activities below.

Introduction

Project 15 is designed to show you how software like Peak LE can be used for desktop digital audio editing (DTP) to produce a wide variety of digital speech, sound effect, and music clips. Peak LE will let you record, edit, and transform digital audio in many very sophisticated ways with very little effort on your part.

If you have not done so, take time to read the modules in Viewport VII on music sampling and digital audio. The data concepts in Module 25 (and earlier in Module 10) will be very helpful for you especially for terminology.

We have provided a folder of short digital audio clips. Look at the files in the "sndproj" folder shown below. Notice the extensions on the files. These are all different file types for audio and audio compression.

Here briefly is the application of each audio file type:

snd	Macintosh system sound files
wav	DOS or Windows sound files
aif	Audio Interchange File Format (AIFF)
au	ULAW sound format commonly used across the Internet (pronounced 'mu-law' audio files as the U is really the Greek mu)

PEAK LE, like many good sound editing software, will read and convert many different files types.
Let's begin. There are six steps to the tutorial on the use of Peak.

Steps:

1. Finding Your Way Around Peak LE
2. Copying, Pasting, and Cropping a Digital Audio Clip
3. Fades, Amplitude, and Envelope Editing of Digital Audio
4. Combining Audio Clips by Manipulating Tracks
5. Reverb, Echo, Equalizing, and other Digital Audio Goodies
6. Recording Your Own Digital Audio Clips

Return to the project menu

Step 1: Finding Your Way Around Peak LE 1.63

Take a look at the window below:

• Load the file "purplepg.aif" in the folder "sndproj" with Peak LE. Run Peak and select Open from the File menu and then select the "purplepg.aif" file. When done, your screen should look something close to the one shown in the figure below.

You will find 2 windows that open:  the transport controls and the waveform edit window.  The larger waveform window will have two parts to it:  the actual waveform (below) and a smaller "Overview" window.  The overview window allows you to quickly travel within large sound files, while the edit window allows you to edit the waveform directly.  If the overview window is not showing, select Show Overview from the Preference menu.

• Let's look around the screen to get our bearings. Using the figure above as a guide, look for the menubar and the toolbar. Find the main Audio Edit window for the sound file your are working on (the main window will always have the name of the file on the top bar).

 
• Find the Transport Controls window. This window serves the same function as the controls on a tape recorder. You can play, stop,  record, and loop the sound clip in the Audio Edit window.

 

Before we start messing around with this sound clip, we will examine one other feature of  Peak LEt. Under the Preference menu select Audio Format (or-I).

This dialog box gives you some key information about this sound clip. The sampling rate is 22 kHz (22.050 technically) and the sample size is 8 bits. The sampling rate could also have been 8 kHz, 11 kHz, or 44 kHz. The sample size could also have been 16 bits. What rate and size you select is always a trade off between the quality of the audio you want and the size of the audio file. See Module 25 in the EMT textbook for more information on this.

Check yourself off on the Project 15 Worksheet when you have completed all of the work for Step 1

Return to the project menu

Step 2: Copying, Pasting, and Cropping a Digital Audio Clip

It is time to start experimenting with the toolbar and the features of a sound editing program like Peak LE. The sound clip that you currently have loaded is a clip from a recording of Northwestern University's Marching Band (purplepg.aif).

Mouse click on the play button in the Transport window to hear this sound clip (the button with the arrow pointing to the right). You will hear that the music starts right in the middle of a phrase and, ends in the middle of a phrase. You can also click in various places in the Overview window to automatically hear the file.  We want to crop the sound clip so that we have only the phrase in the middle.

• Make your display of "purplepg.aif" look something like the one above. Adjust the zoom from the Action menu.

 
• Take your mouse and click-and-drag over the area highlighted in the figure above.

 
• Click on the Play button in the Control window and listen to the playback of the selected area. Does it sound okay? Or, do you need to fine tune it by selecting a little earlier or later of the selection?

 
• Hint: Hold down the Shift key and click before or after the edge of the selection and the highlighted area will change without deselecting the rest of the highlighted area. Experiment with this along with playing the selection until you are comfortable that you have the phrase properly selected.

 
• Select Crop from the Edit menu. Portions of the sound clip before and after the highlight area should disappear leaving only the selection you want.

The resulting Audio Edit window should look like this:

 
• Let's try copying and pasting the waveform. Select the entire sound clip. You can double-click inside of the waveform or pick Select All from the Edit menu. Select Copy from the Edit menu.

 
• We are now going to paste the audio clip at the end of the current selection. This will repeat the the audio clip. Click with the mouse at the end of the current selection as shown on the screen above. Then select the Paste button in the toolbar (to the right of the Copy button).

Position the mouse at the end of this sound clip and paste it again. The end result should look like the figure below.
 


 
 

• Let's save our work as a Real Audio file. Select Save As (not Save) under the File menu so we can save our new version of the work. Change the file format to "Real Audio 3.0" and the extension to the file name so it reads "purplepg.ra". See the figure below.


 

A new window will appear asking for some configuration as to how you wish to present your new Real Audio file.  For the best results, use settings similar to the ones below.   Select the Source window item that most closely matches the audio file you are working with (i.e. voice, voice and music, etc...).  Set the encoder to around RealAudio 28.8.  Experiment with these settings.  Finally, fill in the Title, Author, and Copyright date and make sure Copy Protect is on.  This way no one will be able to edit your files.  Add the Filename ".ra" suffix so that it is readable on PC machines as well.  Click OK when done.  That's it!


 

• To remove a portion of a sound from an audio clip, just select an area of the sound and choose the Cut option from the Edit menu. The Cut option places the clip in the clipboard so you can paste it somewhere else. Try the Cut options on the purplepg.snd sound sample.

 
• Try copy and pasting from two different sound files. You can open the "salsaton.aif" file in a second window in Peak. Copy a brief clip from this drum routine in the "salsaton" window, click on the "purplepg.snd" window, and paste in the sound at the beginning of the clip. (Thanks to the drum line of the Northwestern University band for this clip from their Internet web page.)

Check yourself off on the Project 15 Worksheet when you have completed all of the work for Step 2

Return to the project menu

Step 3: Fades, Amplitude, and Envelope Editing of Digital Audio

For this step let's begin to explore many of the powerful tools that sound editing software provide. We will load the "salsaton.aif" file from the "sndproj" folder and experiment with tools that let you control amplitude.

• Load the "salsaton.aif" file into Peak LE. Go to the Preference Menu and de-select Show Overview.  Your window should have just the waveform as show below.


 
 

• Look at the Audio Format option under the Preference menu to see that this sound sample was recorded at a 22 kHz sampling rate, with an 8-bit sample size.

 
• Play the sound sample. Peak will automatically open a small transport window when you first open the file.  If you have closed the window and want it back, go to the Window menu and select Transport.  Notice in our figure above we have added markers that appear above the graph of the sound. You can add markers by selecting any point in the sound sample (clicking  the mouse over the waveform) and selecting New Marker from the Action menu. You can then click on the marker arrow in the toolbar to access any point quickly and start playing from any point.

 
• Let's try the Fade In and Fade Out options. We can simulate the drums gradually fading in and then fading away as if they were passing us in a street parade (in fast motion!). Examine the figure below. Select the black portion of the sound sample which has been highlighted and then select Fade In from the DSP menu.

The computer will now process the sound sample and reduce the amplitude of the selection starting very low at the beginning and ending with no change. When it is done the graph should look like the one below.



When you select Fade In button, the selected area will be gradually faded in. You can shape this Fade In to any shape you want by going to the Preference Menu and selecting Fade In Envelope.  A new window with a straight line will appear.  Click on various points on the line.  A red dot will appear showing that you've created new edit points.  Click and drag the edit points to anywhere you wish.  To hear your changes, just press the "Change" button.  If you already performed a fade in in the previous step, be sure to do an undo from the edit menu and do another fade in.  If you don't like the envelope you've created, just hit the Reset button and the line will become straight again.


 

• Play the sound sample now and hear the effect.  

  Select the remainder of the file and select Fade Out from the DSP menu.  Don't forget that you can also edit the Fade Out Envelope from the Preference menu in the same manner as the Fade In Envelope.  Your result should look like the graph below. Play the sound sample and listen.

  

  When done with this step, select the Undo option under the file menu. This will undo the fade out.  Select Undo again to undo the Fade In.  Peak has several levels of its undo function.  If you want to save the fade effects, then first select Save As and give the file a different file name.

  Try the following experiment.  Select a portion of a wavefile to either fade in or out.  Get the correct fade in/out envelope from the Preference menu.  Instead of making an envelope, load one from the Load button underneath.  Pick one from the Envelopes folder in the Peak LE folder.
   

• Two other amplitude controls are the Envelope effect and the Amplitude effect. Let's say we need to reduce the amplitude of the entire sound sample to make it soft for background music.  

From the Edit menu choose Select All. Then select the Change Gain option from the DSP menu. When the dialog box is displayed, click the dB window so that it shows percentages rather than decibels.  Set the amplitude to around -20% and click on the OK button. When the processing is completed, you should visually see the difference in your graphic. Select the Play button and listen to the result.


 
 

• You can use the same process to increase the amplitude of a sound. If something was recorded too low, set the amplitude to a percentage in the positive range.  Make sure to click the box next to Clipguard to avoid clipping your signals.

 
• Let's try the Envelope effect next. Select undo from the edit menu to revert back to the un-edited version of the sound file.  Select either all or a portion of the sound file. Go to the DSP menu and select Gain Envelope.  The Gain Envelope works exactly the same way the Fade In/Out Envelopes do.  Click on the line to add points and then move the points to where you want.


 

Hit Change to apply your changes.  Don't forget, if you don't like the envelope, hit Reset and then Change again to set the envelope back to its defaults.

Play the clip and hear the effect. Go back and experiment with some other envelope shapes as well.
 

• That concludes this step which has introduced you to the Fade, Amplitude, and Envelope effects in sound sampling software. Use Save As from the File menu to save a version of the file which you have modified using the techniques learned in this step.

Check yourself off on the Project 15 Worksheet when you have completed all of the work for Step 3.

Return to the project menu

Step 4: Combining Audio Clips by Manipulating Tracks

We will now show you how to work with tracks in a sound sampling program. In the "sndprog" folder there are two files: "waterfal.wav" is a penny whistle recording and "voice.snd" is a recording of spoken voice made on the computer with a microphone. The penny whistle recording is a WAVE file meaning it was recorded on a Windows/PC computer.

• Your task is to import the "voice.snd" file as a second track to the "waterfal.wav" file. You will also want to use the Envelope effect to reduce the volume of the penny whistle while the voice is speaking.

Follow along:

• Open the "waterfal.wav" file from Peak LE and hit Convert and then Done.  Decrease the volume of the sound so that it's not very loud.

 
• Open the "voice.snd" file. Peak will open the file in another window.

 
• Make the Waterfal.wav file active by clicking its window.  Select all and copy the sound.

 
• Select and copy the voice.snd file.  Then click in the waterfal.wav document approximately where you would like the speaking to begin.

 
• Paste the sound file into the stereo document and into the waterfal.wav by going to Edit => Clipboard => Mix.

 
• Move the slider bar to around 80 and hit OK.  The voice is copied into and mixed with the pennywhistle tune.  Play the sound sample to hear your new document.

 
• If you listen carefully to the voice.snd, you will notice that there is a small click in the beginning of the file.  Crop the bad sections of the file out and try pasting the the newer version in.

Check yourself off on the Project 15 Worksheet when you have completed all of the work for Step 4

Return to the project menu

Step 5: Other Digital Audio Goodies

In Step 5, we will experiment with some of the other special effects.  Peak LE contains only the basic DSP tools needed to manipulate files.  Most effects like, Reverb, Echo, Flange and the like are Plug-Ins that are Purchased Separately.  However, Peak LE does come with a few demo Plug-Ins that we'll take a look at now.

Load in the original waterfal.wav sound file for your experimentation.

• Select the entire sound file and go to the Plug-Ins Menu and select The SFX Machine Demo option.  A new window will appear.  Almost all of the effect plug-ins work in the following manner.  You select the type of effect you wish under the Category window.  Then select the Preset (effect configuration) from the next window.  In the window on the far right are controls specific to the effect you are applying to the sound.  Try the following.  Select Chorus and use the 5-Delay Chorus preset.  Move the sliders around to fine tune the effects.  Your screen should look something like the one below.



Experiment with the other effects to see how they work.  Peak will automatically let you preview the effect by playing a small sample of the file in a continuous loop until you click the Preview button.  If you like your changes, select Process.  Depending on the speed and amount of RAM in your computer, these effects may take some time to process.  Be patient!

Use a variety of the special effects to produce your own bizarre version of the Penny Whistle tune. Be sure to save your work when done, and under a new file name.

Check yourself off on the Project 4 Worksheet when you have completed all of the work for Step 4

Return to the project menu

Step 6: Recording Your Own Digital Audio Clips

One powerful feature of digital audio editing software is the ability to record your own sounds, voice, and music. To quickly record music from an Audio CD in Peak, go to the File menu and select Import CD Track.  You will then be asked to navigate to the CD you wish to copy music from.  Select the CD and the track and hit OK.

The next window allows you to select the Sampling Rate and bit depth of the file you are about to record.  Use the slider bar to select portions of the track.  If you click OK without selecting start and end times, you will automatically record the entire track.  Try it now!
 
 
 

Another method of recording sound is to select Record from the Action menu.  A new window will appear asking you to select the device for recording input, and to configure the defaults for the new sound.  Click on the Monitor box to view the sound source as it is playing.  Click on the Microphone input source and then the OK button. You'd use this same input source for a tape recorder plugged into the back of the Mac.

To start recording, press the Record button on the control panel to activate the recording process.

Be careful, digital samples can take up lots of memory!

Record several sound samples of your own. Try different formats. Be sure to use all of the editing skills you acquired earlier in the project activities to edit and enhance your recording. Crop the file, adjust the amplitude, add a little reverb, etc.
 

Check yourself off on the Project 4 Worksheet when you have completed all of the work for Step 6

Return to the project menu

Happy Sampling.....!

Version 1.0
©1996 David B. Williams and Peter R. Webster
Schirmer Books