The media capabilities of our mobile devices are amazing, especially when you consider where we were just a few years ago. The first mass-produced MP3 player was the SaeHan/Eiger MPMan introduced in 1997. The device had 32 MB of storage, enough for roughly 6-7 songs. While this may seem severely limited by today's standards, it was a revolution and offered a new way to listen to music. The history of portable media players is fascinating. For more information, you can refer to http://en.wikipedia.org/wiki/Portable_media_player.

Today's devices are capable of so much more. Portable entertainment devices can play games, video, and all sorts of audio. Although not absolutely required, many apps use sound to some degree, especially if it is to call attention to something important. TweetBot is a classic example of an app that is enhanced by the sound it produces via the user's interactions.

Today's devices can also record audio for a variety of purposes, whether for...