Uniform Distributions of Sound Sources on the Surface of a Rigid Sphere and Some Applications

Abstract

A study is made of certain elementary source distributions on the surface of a rigid sphere for a fairly extensive range of frequencies. The elementary systems considered consist of a point source, uniformly vibrating caps and rings, and plane line sources. Results are given for typical cases of the far zone sound fields and acoustic impedances of caps and rings, and also for the far zone sound field of a particular plane line source. Combinations of the elementary rings and caps are examined with a view to producing desired directional patterns and the results for a particular directional beam are presented. Taking a sphere as a model for the human head, the results for a point source are used to examine possible mechanisms for the binaural localization of sources of sound. These results indicate that, due to non-linear variation of phase with frequency, a pulsed sound should appear in a somewhat different form at each ear. It is suggested that localization is achieved by the brain in reconciling such pulse forms and that time and intensity differences are elements in a much more general process. Another possible application of the results involves the particular line source considered which could be taken to represent a human mouth.