Design and performance evaluation of a broadband three dimensional acoustic intensity measuring system.

A seven-microphone three dimensional (3D) intensity measuring system has been developed and evaluated for performance for a broad frequency band (200 Hz-6.5 kHz). Six microphones are arranged in a concentric array with one microphone at the center of the probe. The screw adjustable center microphone is the probe reference microphone, and is used for calibrations of the other microphones in the probe. This probe addresses limitations of the traditional two-microphone system in measuring acoustical properties in a 3D space from the one dimensional measurements. This probe also eliminates the need of spacers used in the existing 3D probes for broadband measurements. Diffraction and reflection effects on calibrations due to presence of the microphones and the probe supporting structure are negligible. This seven-microphone probe provided better results in the intensity measurements for the wide frequency band than that of a similar four-microphone array probe.