Monopole radiation in the presence of an absorbing plane

Abstract

Two theoretical solutions for the field of a point sound source above a plane boundary between air and an absorbing material are discussed. The validity of approximations based on the plane-wave reflection coefficient and on the modified image method are also examined. Results of measurements made with a source in and above slabs of absorbent material are shown to be in agreement with theoretical results. The performance of free-field rooms having plane absorbent treatment and ground-reflection effects in the measurement of aircraft noise spectra can thus be predicted.