A Study of the Factors Influencing the Damping of an Acoustical Cavity Resonator

Abstract

This paper presents a systematic study of experimentally significant losses contributing to the damping of an acoustical cavity resonator. Absorption measurements in air on the 0, 1 wave of a round cavity were made by a resonance response method employing a transverse particle velocity pickup device. This study reveals that mechanical losses due to the vibrations of the walls are experimentally significant. Empirical relaxation time formulas are established for air at 24 and 27°C. The thermal and viscous boundary-layer loss formula is fitted to these data by choosing the thermodynamic ratio νρ0/μ equal to 1.31.