Effective Modal Density in a Reverberant Sound Field for Finite Sized Sources

Much of the theory concerning the formation of sound fields in reverberant rooms and the measurement of the sound levels produced by these fields has emphasized the statistical aspects. A previous paper [K. M. Eldred, B. H. Sharp, and F. M. Murray, “The Coupling of Finite Sized Sources to a Modal Reverberant Sound Field,” presented at the 76th Meeting of the Acoustical Society of America (Nov. 1968), J. Acoust. Soc. Amer. 45, 338 (A) (1969)] discussed the coupling of finite sized sources to a reverberant sound field and showed that there is a strong dependence between sound level and source configuration in certain frequency ranges. This paper will briefly review these findings and extend the work to examine the relationship between the effective modal density and the calculated modal density as a function of source configuration. On the basis of this relationship, the relevance of statistical methods as applied to reverberant sound fields with finite sized sources will be discussed.