Absorption of Sound in Humid Air at Low Frequencies

Abstract

This paper represents a continuation of the work in absorption of sound in humid air initially reported on at the Fifty-First Meeting. Results have been obtained at temperatures of 0°C and 55°C for the range of pressures from 20 cm Hg to atmospheric and water vapor concentrations from 2% relative humidity to 80% relative humidity, in the audible range 300 cps to 1100 cps. It is found that the absorption coefficients in general closely conform to the Knudsen-Kneser curves but exhibit large departures at extreme relative humidity values. Secondary maxima were not found. (This work was supported by subcontract with the University of Michigan under Signal Corps Contract DA-36-039-sc-52654.)