Capturing, editing and exporting sound files. Digital audio can be used for web-based instruction (including LMS-based courses), educational CD-ROMs, digital video, and podcasting. For our purposes we will focus on how to create, edit and export digital audio files using Audacity, an open-source, cross-platform application.
Often using a combination of digital still images and digital audio is as effective as digital video, but using much less bandwidth. The benefits of using audio to supplement text-based materials are many. These include:
Only few years ago, digitizing audio meant capturing via cassette tape, then importing using a sound card. Today however, the advent of both digital voice recorders, mp3 player/recorders and direct to computer audio capture make the process easier—and less expensive.
Digital audio files are also an integral part of making materials accessible for persons who are visually impaired or blind. Common uses of digital audio for educational purposes include integrating voice and/or music into:
When considering using digital audio, some important questions are:
Podcasting is used across the full spectrum of educational endeavours, from K-12 through post-secondary; podcasting is also becoming more prominent in professional development for educators.
A number of universities, including UBC, are using Apple’s iTunes to distribute podcasts of lectures via an institution-specific iTunes U. UBC’s iTunes U can be accessed here: []
Halton (ON) action research project that included podcasting: []
Taisei Girls’ High School (Japan) Podcast: []
Secondary Worlds podcasts: []
Wicked Decent Learning podcasts: []
Creating a digital audio voice recording has a number of different uses in an online teaching environment. These include:
For our purposes we will focus on how to create, edit and export digital mono audio files directly on your computer, using Audacity, an open-source, cross-platform application.
Audacity is a very comprehensive digital audio editing suite. In fact, many users are a bit intimidated by its interface the first time they run Audacity. Fear not! You need only learn how to create and export an audio file (instructions are below). Ignore the rest, get Audacity to do what you need it to, then go back and try to learn some of its advanced features if you wish.
The benefits of using audio to supplement text-based materials are many. They include:
Only few years ago, digitizing audio was a rather onerous process. It required specialized (and expensive) hardware to convert audio captured via tape, into a digitized format. It was time consuming and the quality of the recordings tended to degrade with each conversion. Once digitized the editing was done on commercial software applications—expensive ones that tended not to run on personal computers.
Today, however, the advent of inexpensive sound cards and software has made direct to computer audio capture easier—and affordable. Most personal computers have an audio input port (as well as USB ports, which also support audio input devices) and a process that can digitally render audio files quickly and cleanly. For material built into a web site, smaller file sizes are better. Smaller files play (or download) more quickly.
Most of us prefer to listen to audio in stereo: sound using two tracks, each somewhat different in the left or right earphone/speaker. However, for spoken word recordings mono—one track, heard in both ears—sounds almost as good while creating smaller audio files. In fact, a mono audio track is precisely half the size it would be as a stereo file!
The standard audio file for music CDs are called WAV files. MP3s produce a comparable quality audio file approximately 10% of the equivalent WAV file.
To create your audio file you will need:
You also need approximately 40MB of hard disk space to install Audacity and its plug-ins, as well as enough hard disk space to hold and edit your audio files. Each one minute of audio created by Audacity uses approximately 6MB of disk space prior to editing or exporting. In other words a 30 minute talk would use around 180MB of disk space.
In addition to the most recent release version of Audacity (not the beta version), you should also download and install the LAME MP3 encoder plug-in for Audacity. This will allow you to export files as mp3s. The mp3 audio codec produces a compressed, high quality audio file—roughly 1/10th of the size of a standard audio CD file (.wav). Smaller files means less bandwidth and faster playback or downloading. That 180MB Audacity file reduces to around 20MB, once we convert it into an MP3 file!
Installing Audacity and LAME
Most computers have built-in microphones; so too do many web cameras. But they tend to do a very poor job isolating voice from background noise. That’s why we recommend you use an external microphone of some sort. Positioning a microphone is very important when recording digital audio: if you capture nice clear audio initially, it will produce a much nicer final clip. There are, broadly speaking, two different types of microphones you can use.
Headset with microphone
One of the benefits of using a headset with microphone is the ease with which you can position the microphone boom (or arm). For Mac users USB headsets seem to work better; for Windows users traditional two plug (one for the microphone port, the other for the speaker port) seem to work better. Seem to is the operative phrase here: your experience might be very different!
Set the microphone boom (or arm) so it is parallel to your jaw line when your mouth is open. This ensures the microphone is close enough to your mouth to clearly capture your voice, but not close enough that your breathing is picked up. Unlike an external microphone, the microphone end of the boom should be closer (around 2 cm) to your chin.
Creating a new recording on your computer
It’s time to get started! The general process for recording audio is:
Ideally you should be in a quiet room with all windows and doors closed. You should also put a large Do not Disturb – Recording Session in Progress sign on your door. Turn off (don’t mute) your mobile phones, pager, and any landline phones in the room. Will you be recording from a script? If so you need to write, edit, and print it in a format that’s easily readable whilst recording. We suggest printing double-spaced, single sided, and using a font of 14 point or larger. Don’t staple pages together; simply stack them in order and quietly slide one out of the way to reveal the next page as your read. If you are recording an interview or conversation, position the microphone on a surface midway between the two of you. Sit as closely (but comfortably) as possible.
Your computer is up, your microphone is plugged in. Let’s do a test recording!
If your voice sounds very soft, or the microphone is picking up a lot of background noise, move it closer to your mouth. If your can hear your breathing or your voice is causing the sound to break up, move it a bit farther away from your mouth.
Repeat the testing until you find a good position for your microphone or headset. Once you find one that works, take note how everything is set up.
Saving and exporting
To Save your digital audio file, click the File menu, then Save Project As (File/Save As). Enter a name for your recording and save it wherever you prefer in your computer’s filing system. The file is saved as an Audacity project (.aup) file. Audacity will create a file with your project’s name and an accompanying folder that holds the component parts of the project. Be sure to keep both the .aup file and the folder.
Audacity project files are excellent for capturing and editing audio, but they are rather large—too large to be played on the web. The .aup file format is also a proprietary format, meaning very few applications can play it back besides Audacity. Therefore it’s important to Export your recording into a more user (and design) friendly format.
You can export the file in CD quality (WAV format), but that’s also a very large file. But more often we want to export the file as an MP3, since they are smaller. If learners will be listening to the audio file via computer (either embedded in a web page or via an MP3 player like iTunes, Windows Media Player, Real Player, or QuickTime) or a portable mp3 player like an iPod, MP3 is a much better format.
To produce an MP3 version of your digital audio file choose File/Export as MP3.
Note: the default settings on your computer may be for stereo (two track) recordings. The “official” Recording with Audacity tutorial explains how to adjust these settings. Practice Before you try to create your first useable digital voice recording, practice! Follow these steps 3, 4, 5 or 10 times in a row—however many times you need. You have practiced enough when you can consistently produce a high quality sound file quickly and easily!
Write an entry for your course weblog about your experience here (on your "Home" page and posting a new entry). How labour intensive was the process? What worked well? What was challenging? What surprised you?
“Official” tutorial: http://audacity.sourceforge.net/manual-1.2/tutorials.html
Audacity wiki tutorials: http://audacityteam.org/wiki/index.php?title=Tutorials
Audacity podcasting tutorial: http://www.how-to-podcast-tutorial.com/17-audacity-tutorial.htm
GuidesandTutorials.com Audacity tutorial: http://www.guidesandtutorials.com/audacity-tutorial.html
Kent State University Audacity tutorials: Kent State University Audacity tutorials
There are also numerous Audacity video tutorials on YouTube: http://www.youtube.com.