In Your Classroom: Audio Files

by Jerone Mitchell     Department: In Your Classroom

The discussion of digital audio vs. analog audio is an interesting one, and one without a clear answer.  Part of the difficulty is with the fact that, quite often, we don't really know a lot about either subject.

The recording of analog audio has a long history, beginning in the late 1800's with Thomas Edison recording his famous recital of "Mary Had A Little Lamb."  A fairly detailed history of recording technology, beginning with Edison's recording right through the creation of the iPod, can be found here.

Of course, simply learning the history of the technology is not the most interesting way to understand how it works.  A professor at SMU, William Milton Gosney, Jr., created an excellent project in which the students build a speaker using very simple household materials: scissors, paper clips, glue, a small Styrofoam bowl, and a small Kleenex box.  Instructions for this project can be downloaded here.

Another part of the reason why thoughts on analog sound vs. digital sound are not clear is that all digital recordings are not the same.  When you record a sound digitally, you are taking a number of numeric "snapshots" of what the sound is like at a given moment.  The more snapshots you take, the closer it is to the original sound.  The measurement for how often you take these snapshots is known as the Sampling Rate. A fairly simple lesson on sampling rate can be found here.

It's interesting to record a sound at different sampling rates and listen to the difference between them.  A free sound editing program, Audacity, can be found here.   Besides recording at different sampling rates, there are a host of possibilities once one looks at digital recordings as numbers that represent the sound. Just like any other number, these snapshots can be manipulated for various effects.  Reversing the sound, changing the volume, and changing the pitch of the sounds recorded are a few of the activities available.  A video tutorial for Audacity can be found here; in this tutorial, instructions for creating fades, amplifying volume, and editing sound are included.

Another bonus to digital music is that it can be easily manipulated and edited.  For example, you can very simply create songs digitally by combining snippets of music (called "samples") together -- placing a drum sample for percussion underneath a piano sample and/or a horn sample to make a song.  Among the free digital music arrangement programs available is the Trial version of Magix Music Maker 11, which can be found here.

Finally, no discussion of digital audio would be complete without a discussion of the Internet.  Whereas a large amount of press is given to the legal and illegal downloading of copy written music, another frequent usage of new digital audio capabilities is the "podcast," a digital recording of one's thoughts and/or opinions for broadcast via the Internet.  It is not a huge leap to use podcasts within a school environment; a school newsletter can easily be converted into a school podcast, as an example.  If you have already downloaded Audacity, and you have access to an Internet webhost, you have the tools to create school-based podcasts.  A set of instructions for the creation of a podcast can be found here; like the earlier tutorial, this also has a video component.

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