Pressure distribution in a fluid due to the axial vibration of a rigid disc

Abstract

The advent of broadcasting has stimulated scientific interest in the reproduction of sound by the aid of moving diaphragms. There is a distinct change in the quality of reproduced music according as one stands in front or at the side of a loud speaker. This is due to non-uniform pressure distribution from the diaphragm at various frequencies. When the wave-length of sound is comparable with the radius of the diaphragm there is a focussing effect. This occurs at the higher audio-frequencies and upsets the tonal balance unless the listener is situated on the axial line of the diaphragm. The purpose of the present paper is to examine analytically the pressure distribution in the space surrounding a flat rigid disc vibrating in a plane of infinite extent. The plane prevents interference of the sound waves emitted by the two sides of the disc.