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Abstract:
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A problem of practical interest when dealing with outdoor acoustic measurements isto estimate the noise contributions from di erent directions around the measurementpoint. This estimation can be done by means of microphone arrays. More speci -cally, circular arrays are suitable for this purpose as, in combination with proper signalprocessing techniques, they are capable of mapping the sound eld in a plane over 360 .Two processing techniques meant to be used with circular arrays are implemented:the `classical' Delay-and-Sum beamforming and a novel technique called Circular Harmonicsbeamforming. The latter is based on the decomposition of the sound eld inseries of circular harmonics. The performance of these beamforming techniques is analyzedby means of simulations and evaluated by two parameters, the resolution andthe maximum side lobe level.Making use of the results of the simulations, a circular array has been designed forthe localization of environmental noise sources around a measurement point. Finally,a prototype implemented in accordance with the design has been tested in anechoicconditions. The results, which agree very well with the simulations, reveal that thearray is suitable for the purpose of concern. |
