Sound insulation refers to the act of impeding the transmission of sound from one area to another or from a source to a receiver. Typical examples include the sound insulation between adjacent apartment units or between a busy highway and one’s bedroom. The best way to improve the insulation between two areas typically involves the use of heavy materials such as concrete or gypsum board.

Sound absorption refers to the phenomenon whereby some or all of the sound energy incident on a surface is either converted into heat or passes through the absorber. For this reason, good sound absorbers do not necessarily make good sound insulators. Absorption typically should not be the primary means of achieving good sound insulation.