The VLAA: a Very Large Acoustic Array

摘要

A very large acoustic microphone array is described for use in the audio frequency band from 300 to 3000 Hz. The array used constant aperture processing to provide 10 wavelengths of aperture over the entire band, resulting in a narrow but constant beamwidth for all frequencies. The array was electronically steerable in azimuth over a +/- 80-degree range with no grating lobes. Several different embodiments have been constructed, and one design featured steerability in both the elevation and azimuth planes. This array used vertical subarrays at each horizontal array station that were pre-sleered in elevation using a novel analog delay-and-sum beamformer. Signal processing was accomplished using a desktop PC. The large number of microphones used to construct the arrays demonstrated exceptional wind noise averaging in outdoor conditions. Array details, processing methodology, and test results are presented.