Acoustic Impedance of a Right Circular Cylindrical Enclosure

Abstract

At low frequencies, the acoustic impedance of a right circular cylindrical enclosure (containing air, or other gases) is affected by the cooling effects of the walls. Analytical expressions for the temperature distribution have been obtained, and computations of the effect on the impedance are given in the form of plotted correction factors. These corrections are used in making absolute pressure calibrations of condenser microphones at low frequencies. The solution presented for the average temperature distribution applies also to the heat-conductivity problem of a uniform volume distribution of sinusoidal heat sources, which are considered to be in phase, inside a cylindrical enclosure having isothermal walls.