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J Acoust Soc Am. 2005 May;117(5):2866-72.

Time reversal of noise sources in a reverberation room.

Author information

  • 1Laboratoire Ondes et Acoustique, CNRS/ESPCI/Universit√© Paris VII, UMR 7587, 10 rue Vauquelin, 75005 Paris, France. Guillemette.ribay@loa.espci.fr

Abstract

Usually, time reversal is studied with pulsed emissions. Here, the properties of time reversal of the acoustic field emitted by noise sources in a reverberation room are studied numerically, theoretically, and experimentally. A time domain numerical simulation of a two-dimensional enclosure shows that the intensity of a time-reversed noise is strongly enhanced right on the initial source position. A theory based on the link that exists between time reversal of noise and the "well-known" time reversal of short pulse is developed. One infers that the focal spot size equals half a wavelength and the signal to noise ratio only depends on the number of transceivers in the time reversal mirror. This last property is characteristic of the time reversal of noise. Experimental results are obtained in a 5 X 3 X 3 m3 reverberation room. The working frequency range varies from 300 Hz to 2 kHz. The ability of the time reversal process to physically reconstruct the image of two noise sources is studied. To this end, care is given to the technique to separate two close random sources, and also to the influence of temperature fluctuations on the focusing quality.

PMID:
15957757
[PubMed - indexed for MEDLINE]
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