I like to use Audacity, a free, easy-to-use and multilingual audio editor and recorder for Windows, Mac OS X, GNU/Linux and other operating systems, when working with teachers on multi-media projects that require sound. The folks at makeuseof.com have written about three tips for enhancing a recorded interview. If you have ever wanted to learn how to remove background noises, amplify quiet voices, or add a nice musical introduction to your recordings, then check it out.
I had the opportunity to use each of these tips on a classroom project this year. Students in a Mass Media class rewrote a children's story in modern terms and then recorded the story. As you can imagine, in a classroom there is often background noise to remove. We also had some "soft-talkers", so the amplification tip is worth learning. We also adjusted the speed and pitch of the voices at various times to sound like insects and other mammals, but that is another story. Finally, we did use the fade-in and face-out tip for adding music and other sound effects. In the end, we had a pretty good product. So good, that we visited an elementary school and played the recordings for a first grade class.
So if you use audio in your classroom, learning a few of these tips is worth the time.