A hybrid modal analysis for enclosed sound fields and its applications

Abstract

In 1939, Dr. Dah-You Maa presented a paper entitled "The Distribution of Eigentones in a Rectangular Chamber at Lower Frequency Ranges" [D. Y. Maa, J. Acoust. Soc. Am. 10, 258 (1939)]. Since then, his interest in room acoustics has not diminished. More than six decades later, Maa proposed an idea of adding a monopole solution to the normal modal expansion to improve the accuracy in simulating the near-field sound field in rooms [D. Y. Maa, Acta Acust. (Beijing) 27, 385-388 (2002)]. Following this idea, a hybrid model that combines the free field Green's function and a modal expansion has been proposed by the authors based on a rigorous mathematical derivation [B. Xu et al, J. Acoust. Soc. Am. 128, 2857-2867 (2010)]. The hybrid modal expansion can be further extended for complex sound sources by introducing the multipole expansion to the solution. In this paper, the theoretical derivation of the hybrid modal expansion will be reviewed, followed by examples demonstrating the use of the hybrid modal expansion in real-world applications. © 2013 Acoustical Society of America.