Investigation of absorption coefficient measurement of acoustical materials by boundary element method using particle velocity and sound pressure sensor in free field

摘要

There are many methods of measuring the absorptioncoefficient or the acoustic impedance of acoustical materials.For the normal incident absorption coefficient and acousticimpedance measurement, the method using the impedance tube[1] may be used. In this method, however, the dimensions of theimpedance tube limit the frequency range in which the valuecan be properly measured, and also, the specimen must be cutout from a large material block. Moreover, the measured resultsof the large material block itself and of the small cut specimentend to differ when the specimen is a poroelastic material.