Multi Acoustic Prediction Program (MAPP) Recent Results

The Meyer Sound Multi Acoustic Prediction Program (MAPP) is an ongoing research program to develop and distribute sophisticated software for accurately modeling the acoustic interaction of loudspeakers. Currently, we use a far-field model of acoustic interaction, based on the empirically measured far–field polar patterns of loudspeakers. Using a rotation device in an anechoic chamber, we position the loudspeakers every degree both horizontally and vertically, for a total of 360∗180 = 64, 800 measurement locations. We use a multiple timescale FFT based measurement system, which gives us at least 1 24 octave resolution in the audio spectrum 20Hz → 20kHz. The resulting data sets are large, approximately 1.5 ∗ 10 bytes, (1.5 gigabytes) for each loudspeaker. For this reason, we have chosen a distributed client-server approach to software development. A Java based client program resides on a personal computer. This client takes care of the visualization and display of the acoustic information. The client program connects through the Internet to our computational servers based in Berkeley, California, which handle the numeric model computations. In order to test our model and measurement facilities, we have constructed an ideal (in the classical physics sense) model loudspeaker, which consists of a well-behaved 3 inch cone woofer placed on the surface of a hard 10 inch radius sphere. Because of the simple geometry, it is possible to derive a solution to the complex pressure radiated by this loudspeaker using a simple recurrence relation and the sum of Spherical Hankel functions. Also, this geometry has the advantage of being rotationally symmetric, allowing for a great reduction in the number of empirical data points needed.