Application of audience-seats characteristics to the sound field analysis for large enclosures

The analysis of the sound field of a hall including the effect of audience seats has difficulties in computing time and memory. Although extensive investigations have been conducted for analyzing sound fields, there is scarcely any report dealing with the sound field including this effect. The main cause may be the complex shape and amount of materials of the audience seats. However, there is a possibility that periodical grooved structures like seat rows can be replaced by an appropriate imaginary boundary with an impedance of quasi-local reaction at the top of seats. The purpose of this research is to reduce the calculation load of acoustical analysis by treating the seat rows as an imaginary-impedance boundary which is almost equivalent to the characteristics of audience seats. The SDE filter, which can express excess attenuation caused by seat rows, is proposed and some applications to both the geometrical and wave theoretical methods are presented. To examine the validity of this method, some numerical examples calculated using an image method are discussed in comparison with the measured data. Furthermore, the numerical results of its application to the boundary element method are presented and discussed in terms of its effectiveness and validity.