Method for calculating the absorption of sound by the atmosphere

Abstract

The aim is a standard method of calculation with the credibility necessary to support major compromises between economic and environmental benefits desired by society. A two-relaxation model for the absorption of sound in air is fitted to a maximum of available laboratory and field measurements, as well as the detailed knowledge of basic mechanisms described in the previous paper. In this way, a set of seven fairly simple equations are generated whose form is determined by the physical nature of the mechanisms. These formulas may be used to compute the absorption of a pure tone over the following range of variables to an estimated accuracy of ±(10 + 1.5|t − 20|)%: frequency/pressure 102 to 105 Hz/atm, temperature (t) 0° to +35°C (32°−95°F), relative humidity 10%–100%, pressure 2 atm or less. A method of corrected the result to apply to bands of noise is proposed.