Sound source characterisation: The focussed beamformer vs the inverse method

Holland, K.R. and Nelson, P.A. (2003) Sound source characterisation: The focussed beamformer vs the inverse method. In Proceedings of the Tenth International Congress on Sound and Vibration. International Institute of Acoustics and Vibration. 3499 - 3506 .

Abstract

The current availability and affordability of multi-microphone array systems has awakened a strong interest in sound source location and characterisation in many fields of experimental acoustics. Although the theory behind the design of such arrays has been known for some time, the algorithms used to process the microphone signals are the subject of on-going research and development. The beamformer algorithm is well-known and relatively simple to implement. It is useful for 'scanning' an area to find the position of sound sources but has limited source characterisation capability. The inverse method, on the other hand, requires prior information on the position of sources, is harder to implement but can yield realistic source characterisation data. This paper details a comparison between the two methods based on experimental data. The inverse method is shown to perform better than the beam former when more than one source is present as the output from the beamformer is shown to be dependent upon the degree of coherence between multiple sources whereas that from the inverse method is not. It is demonstrated that both methods can be used effectively under reverberant conditions through the use of measured Green functions in place of the simple geometrically-derived free-space ones.

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Contributors

Author: K.R. Holland

Author: P.A. Nelson

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