Effect of Humidity on the Absorption of Sound in Air

Abstract

The absorption of sound in air as a function of humidity has been measured over the frequency range from 1400 to 17 000 cps. The reverberation chamber method was used with one chamber of dimensions 26 by 16 by 12 inches. The wall absorption and classical air absorption of the chamber were determined by calibration measurements using dry air. The study was conducted using broad-band noise as a sound source. The absorption was determined for certain frequency bands by the use of band-pass filters in the receiving system. The resultant curves of the air absorption coefficient versus percentage of water molecules follow the same general shape previously calculated and measured by others, but the maximum value is somewhat lower and the curves exhibit minor maxima in addition to the usual major maximum.