Investigation of sound transmission properties of a medium resulting from sound wave compensation caused by other sound sources

Abstract

The aim of this work is to investigate sound transmission properties in relation to the conditions of medium excitation by both the primary and the secondary sound sources. A primary source is understood to be an independent sound source; a secondary source is defined here to be a resonator, or system of resonators, re-radiating an acoustic wave from the primary source. Destructive interference of acoustic waves may occur at a given point in the sound field when both a primary and a secondary source are present and at the given point the phase of the pressure produced by the secondary source has an opposite sign to the phase of the wave from the primary source. Also a change of the radiation conditions experienced by the primary source is possible depending on the properties of the acoustic field. Because of its practical importance, the term “compensation” of sound pressures is introduced here to refer to destructive interference among many sound waves. The results of investigations of such destructive interference conditions in a plane wave acoustic pressure field and in a direct wave field are presented. Some possibilities of changing sound transmission properties by applying compensation methods are shown. These may be of some practical importance when dealing with the possibility of limiting noise propagation.