Fluid-borne acoustic energy transfer in complex multienclosure systems

Abstract

The diffuse field equations of architectural room acoustics are used to derive an engineering model of the fluid-borne acoustic energy transfer in complex, multienclosure systems. This coupled enclosure model relates unknown internal-enclosure sound-pressure levels to known external boundary sound-pressure levels. It is defined by a set of matrix equations relating internal enclosure intensities to external boundary sound-intensity loadings. These equations result from considering an energy balance for each enclosure including internal absorption and feedback energy transfer with nearest neighbor enclosures having common wall boundaries. Measured and/or calculated transmission and absorption acoustic energy partition coefficients at normal incidence are used to define the enclosure-enclosure interaction and external boundary-enclosure compatibility coefficient matrices over frequency and ambient pressure, etc., ranges of interest. An inverse formulation of the coupled enclosure model is given for the evaluation of unknown external boundary loadings from known but incomplete enclosure sound-pressure-level measurements. Nondimensioned results are presented which show the application of the coupled enclosure model in submarine habitability, self-noise suppression, and airplane-minimal added weight contexts as a function of acoustical material treatments.