In my search to understand exactly what a decibel is, i came across this site. It contains with several very informative links about sound, noise, acoustics and computer noise reduction. I did searches in the forums and as far as I can tell this is not a duplicate post but if it is feel free to flame
http://www.catb.org/~esr/writings/ultimate-linux-box/references.html
http://www.catb.org/~esr/writings/ultimate-linux-box/references.html