Passive imaging of scatterers in an acoustic daylight imaging configuration

Abstract

The arrival-time structure of Green’s functions is extracted by crosscorrelating one-sided aeroacoustic surf noise in an acoustic daylight imaging configuration, where 14 microphones (separation 0.08-3.7 m) are located between the noise and a cylinder. The cylinder is a hollow PVC pipe (radius 20 cm, height 2 m) 2.5 m landside of a microphone array. The frequency band for computing the cross correlation function is 400-2000 Hz, and total averaging time is Tave = 3 min. Results show that arrivals corresponding to the scattered (travel-time for source-scatterer-receiver path) waves and the time-difference (travel-time difference between two scatterer-receiver paths) waves emerge in the crosscorrelation functions for an acoustic daylight imaging configuration. Only one microphone pair is needed to locate the scatterer passively with the scattered and time-difference traveltime. We show imaging of 20 crosscorrelation functions with clear time-difference and scattered waves. Each estimated location is along th...