An experimental study of controlling the sound distribution in a tube by using auxiliary driving sources

Abstract

This paper deals with an experimental method of actively controlling the sound distribution in a tube. A tube is driven by a simple harmonic sound source and the sound wave pattern inside the tube is controlled by applying external (control) sound sources which are electrically connected to the driving source. The control is achieved by chaing the position and magnitude of the control sources. It is experimentally shown that it is possible to reduce the sound energy over a portion of the length of the tube without reducing and the same time the sound energy over the remaining length of the tube. Possible application to the control of transmission of noise through air-conditioning ducts has also been discussed.