Concrete construction of a telescopic microphone system equipped with a spherical array and its experimental evaluation

We have designed and constructed a prototype of computer-aided microphone systems with analog devices. It consists of 24 microphone channels. Each is equipped with 47 microphones arranged symmetrically around the array center on each of 4 arcs. By calibrating the mean relative gains and time delays of the microphones used, the experimentally evaluated sensitivity distributions of the constructed system for sinusoidal and band-passed signals of various frequency and bandwidth, and the SNR of the system well coincide with the theoretically expected result, while the relative RMS error of the received signals exhibits slightly large values compared with the theoretical one, which shows the necessity of further compensation of the relative frequency amplitude and time delay characteristics of the microphones used