CONDENSER MICROPHONE MODEL - I - APPLICATION OF THE T-MATRIX METHOD OF WATERMAN TO ACOUSTIC SCATTERING FROM AN ELASTIC OBSTACLE

Acoustic scattering of a plane wave from a condenser microphone is inv estigated-and the eigenfrequencies of this coupled acoustic system are calculated. The wave is incident parallel to the axis of a rigid cyli nder, closed at the bottom by an elastic membrane. To take into accoun t the normal modes inside the cylinder a Green's function method is ap plied. Outside the scattering and interaction of the incident plane wa ve with the microphone is treated analytically using the transfer-matr ix method of Waterman. Good agreement of the eigenfrequencies with mea surement is achieved, but only for obstacles which are not too small, i.e., the wavelength is comparable to the dimensions of the microphone (radius a of the microphone membrane is greater than 0.015 m). (C) 19 98Acoustical Society of America. [S0001-4966(98)05908-6].