波数・周波数スペクトル測定用マイクアレイのマイク配置の最適化

抄録

In order to develop microphone array for the wavenumber-frequency spectrum analysis that separates the hydrodynamic pressure fluctuations (HPF) and acoustic pressure fluctuations (APF), it is necessary to consider the spatial resolution to capture both eddy scale of the turbulent flow and wavelength of the sound which has relatively large scale compared to the flow eddy. In this study, the effects of the number of microphones and their arrangement on the accuracy of the analysis were investigated, and the optimized microphone array arrangement was explored. The results of comparison of the wavenumber-frequency spectrum indicated that the microphone array with a well-balanced combination of sparse and dense microphone arrays (such as the logarithmic spiral array and localized random array) of 96 channels or more is required to separate APF and HPF in the frequency band of 500~5 kHz which is required for the analysis of automobile aeroacoustics noises.