Charles is looking for some help with a project, read the challenge and post up in the comments if you have ideas! "When you listen to music or speech in a noisy environment you have to constantly, continuously adjust the volume control: boost the gain when the sound level is low, reduce the gain when the level is high. For example trying to listen to a movie in an airplane, or to a program in a car. What's needed is a gadget that automatically changes the gain of the amplifier, as a function of the average sound level, to reduce the dynamic range of the sound source -- an audio compressor."
http://blog.makezine.com/archive/2005/11/make_challenge_auto_gain.html