Acoustic modeling and analysis of enclosed cavities using structural-acoustical experimental models

In this study a Multiple Input/Multiple Output structural-acoustical model is developed based on experimental data. This model is used to analyze the interior sound field of enclosed cavities and also predict the effects of structural dynamics modifications at the boundaries on the interior sound pressure. The model inputs are acceleration signals from each of the candidate noise sources, and the outputs are sound pressure signals from two closely spaced microphones.;The specific acoustic impedance and acoustic particle acceleration are estimated and used to separate the sound pressure into its progressive and standing wave components. Acoustic particle acceleration mode shapes of enclosed cavities are obtained experimentally and are found to compare very well with analytical and finite element results. The model methodology allows for noise source identification, source separation and ranking, and sound field decomposition. A unique model capability is the prediction of the interior sound pressure due to structural modifications at the boundaries based on experimental data.;The underlying theory of the method is presented and applied to several laboratory tests to demonstrate the capabilities and limitations of this model. The results illustrate the noise source identification and sound field decomposition capabilities of the model. Predicted interior sound pressure values due to mass modifications at the boundaries are compared with actual results. For small mass modifications relative to the weight of the cavity panel it was found that predicted results compared very well with actual experimental values.