The instantaneous spreading apart of air particles during the negative going half cycle of a sound wave. The opposite of condensation.
"About Beta to DVD conversion: My wife and I have experienced the thrill of our life, seeing our now 22 year old daughter and 18 year old son's collection of infant birthday parties, transferred from the now extinct Beta Tape format, to crystal clear DVD. It was hard to hold back the tears of joy seeing these forgotten videos. It brought back so ..."