A further study on coherence between virtual signal and physical signals in remote acoustic sensing (L).

A recent paper by Zhang, Wang, Duan, Tao, Zou, and Qiu [(2022). J. Acoust. Soc. Am. 152, 2840-2848] proposed that the average distance between physical microphones in remote acoustic sensing should be no larger than half the wavelength to ensure the coherence between the virtual signal and physical signals no less than 0.9 in complex sound fields. In this letter, the effects of the sound sources' distance on the coherence between the virtual signal and physical signals are further investigated, and it is found that the required average distance among physical microphones becomes smaller when sound sources are closer to the microphones.