Reciprocity Technique for Analysis of Sound Radiation from Vibrating Components of Vehicles. 1st Report. Measurement of Acoustic Transfer Functions.

Abstract

A technique based on the principle of acoustic reciprocity has been developed for measuring acoustic transfer functions for sound radiation from vibrating components of vehicles. With this technique, frequency response functions of sound pressure on the surfaces of components are measured with loudspeakers installed at receiver points. In this paper we will first explain the acoustic reciprocity principle for coupled structural-acoustic systems, realization of a simple sound source, measurement of effective volume velocity of a sound source and signal processing. Empirical examples will then be given of applications of this technique to the analysis of sound radiation from the engine of a passenger car. The results indicate that the reciprocity technique is often more accurate than the conventional acoustic excitation method which uses loudspeakers installed on the surfaces of components.