IMPULSE-RESPONSE FUNCTION FOR A SCALAR WAVE SOURCE IN A COMPLIANT BAFFLE

The velocity potential impulse response function is computed for a cylindrical piston in a compliant baffle. It is shown that, in general, the impulse response is that of a piston in a noncompliant baffle, plus a small wake, or reverberation, which dies out in a time the order of the transit time of the wave to the point in space. The slow decay of the wake means that the energy in the wake from a short pulse will be considerable fraction of the total energy. The solution is obtained in closed from from a baffle which matches the fluid impedance. Second sound heat pulse propagation in helium II obeys the scalar wave equation and it will have a second sound heat pulse impulse response which is isomorphous with that of the pressure wave in a fluid. It is pointed out that the analyses of the transient electromagnetic field of a vertical dipole antenna above a conducting earth, and the seismic transients in a layered earth can be of use in discussing the acoustic problem explored here. © 1979, Acoustical Society of America. All rights reserved.