Reverberation effects in acoustical resonators used for bubble measurements

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Attention has recently been drawn to the potential for errors to arise in the classical interpretation of bubble behavior in a reverberant cavity. The bubbles contribute to the reverberant field and, in a reciprocal effect, their response is modified by it. These reverberant loading effects have been shown to be important in the case of a bubble placed in a reverberant cavity. Here, the related topic of reverberant loading in a parallel plate acoustical resonator within which the bubbles are randomly distributed is addressed. Calculations are carried out for random bubble distributions consistent with measured populations. It is shown that, although large reverberation effects do occur, these are confined to relatively narrow bandwidths. Only when these narrow bands coincide with the resonator harmonics are resonator measurements significantly affected. For the specific geometry used to measure ocean bubble populations, reverberation effects turn out to be small. Other resonator dimensions or designs, however, could lead to greater effects, and the calculations presented here emphasize the importance of properly evaluating the reverberation influence for any specific application. Procedures for implementing corrections are identified. © 2005 Acoustical Society of America.

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Journal of the Acoustical Society of America