A Study on Minimising the Errors on the Boundary Conditions when Using an Equivalent Source Technique for a Modelling of Sound Field inside an Enclosure

등가소스법을 이용한 공간 내의 음장 모델링에서 경계면 조건 오차의 최소화에 관한 연구

The equivalent source method is used to calculate the internal pressure field for an enclosure which can have arbitrary boundary conditions and may include internal objects which scatter the sound. Some of the equivalent positions are chosen to be the same as the first order images of the source inside the enclosure, some are positioned on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. The convergence of this method is checked by evaluating the velocity error at a larger number of monitoring positions. Example results are presented for various numbers of sources and evaluation points. The results showed that in general the more equivalent sources increased the accuracy of the sound field predictions but the accuracy is not too much sensitive to the numbers of evaluation points.