IT is an anachronism that the stethoscope, introduced in 1819, remains an indispensable medical tool today although no standards have ever been set for its acoustical performance.' Neither has a standard test been established for evaluating the acoustics of the intact instrument. Furthermore, there is no information on the intimate acoustical interaction of the stethoscope with the doctors' ear...

In this paper, a method is presented for modeling sound propagation in rooms using a signal processing approach. Low order digital filters are designed to match to sound propagation transfer functions calculated from boundary material and air absorption data. The technique is applied to low frequency, finite difference time domain (FDTD) simulation of room acoustics and to real-time image-sourc...