Multi-variate error analysis of beam-forming acoustic measurements in a wind-tunnel
Ramani Ramakrishnan, Greg Kawall, Pushpinder Singh Bhullar, Norman Ball · The Journal of the Acoustical Society of America · 2005
Source localization has been in the forefront in acoustics, since quantification of the source power and its exact location is de rigueur for successful noise control. Starting from single microphone measurements, many different methods, progressively more successful and complex, have been attempted for source localization. Recently, beam-forming methods, due to their success in underwater acoustics and architectural acoustics, have been used in wind tunnel tests. These tests have been quite extensively utilized both in automotive and aircraft tests. Beamforming techniques use an array of microphones, arranged in different patterns, to detect the source location and source power. In beamforming, the array in effect beams, not in the physical sense, towards the source to determine its position. Various parameters determine the success of the beamforming techniques. Some of these parameters are: number of microphones, microphone spacing, array pattern, source frequency and signal analysis procedures. A series of microphone array tests were conducted at the national Research Council of Canada’s wind tunnel, with and without flow. The source location was known a priori. A multi-variate error analysis was performed to determine the importance of the different parameters. The results of the analysis will be presented in this paper.