Comparison of multi-microphone probes and estimation methods for pressure-based acoustic intensity

Abstract

Acoustic intensity measurements made with multi-microphone probes traditionally use cross-spectral processing methods to estimate pressure and particle velocity. Bias errors become significant as the microphone separation becomes comparable with the acoustic wavelength. However, it has been shown that the phase and gradient estimator (PAGE) method increases probe bandwidth without modifying microphone spacing [Thomas et al. J. Acoust. Soc. Am. 137, 3366-3376 (2015)]. In this study, acoustic intensity is estimated by both the PAGE method and the traditional method across two three-dimensional (3D) intensity probes and three 2D intensity probes. Probe performance is compared in the far field of a broadband noise-radiating loudspeaker located in an anechoic chamber. The results show increased frequency bandwidth using the PAGE method across all probe designs. For 3D probes, intensity level errors were least with a spherical probe. For the 2D probes, the accuracy of intensity level and direction estimates increased with the separation distance of the microphones.