| The acoustic radiation patterns above a controlled source have been studied using the nearfield acoustical holography (NAH) technique as the temporal and spatial coherence of the source was systematically degraded. To permit the application of the NAH technique to the study of temporally and spatially incoherent sources, a high-speed data acquisition system which provides virtually simultaneous sampling of the acoustic pressure on a plane, and a special purpose digital noise source, were built. The acoustic radiation patterns above a baffled dual piston source driven with a variety of signals, including broadband noise, were modeled theoretically and measured experimentally. |
