Measurement accuracy of a one-dimensional four-microphone sound intensity probe

Abstract

In the sound intensity measurement, it is important that a microphone probe does not disturb the sound field. A side-by-side or a face-to-face configuration is most commonly used for the microphone probe. With these conventional configurations, however, two tubes containing individual preamplifiers are parallel and close to each other and cause a diffraction problem. A recently developed one-dimensional four-microphone probe is structurely much simpler than conventional probes. Two microphone pairs cover low- (50–800 Hz) and high- (800-10 kHz) frequency ranges and, therefore, it is possible to measure the whole frequency range without changing the microphone distance. The effective distance between pair microphones, pressure, particle velocity, and active intensity responses are measured in an anechoic chamber. Assuming a farfield condition, the measurement accuracies of pressure, particle velocity, and intensity responses are checked by comparing these with the pressure of a reference microphone. The accuracy of the reactive intensity measurement is checked by measuring the pressure square gradient by a reference microphone. The results will be shown at the meeting.