Spatial distribution of energy in SEA acoustic volumes

Abstract

Statistical energy analysis (SEA) methods predict the space average energy in acoustic volumes. The predicted SEA acoustic energy levels are converted to SPL levels using the assumption that the sound field is diffuse. The SEA prediction methods estimate a single, space averaged value for the acoustic energy in the enclosure, whereas the theory of diffuse sound fields in enclosures predicts a nonuniform energy distribution in the enclosure. The energy levels and SPLs increase near the boundaries of the enclosure. The theory of diffuse sound fields can therefore be applied to generate an estimate of the spatial distribution of sound energy from the predicted spatial average. The sound field distributions are based on the Waterhouse corrections for reverberation rooms [Waterhouse, J. Acoust. Soc. Am. 27, 247–258 (1955)]. The use of the Waterhouse correction in the interpretation of SEA predictions is most useful in acoustic volumes which are relatively small in relation to the acoustic wavelengths of interest. Enclosures which have dimensions on the same order as the acoustic wavelengths are commonly encountered in transportation systems such as automobiles and airplanes.