Active Control of Sound Intensity for Suppression of Reflected Sound Waves Based on the State Feedback Control

Hironobu TAKAHASHI  Yoiti SUZUKI  Shouichi TAKANE  Futoshi ASANO  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E84-A   No.4   pp.1017-1026
Publication Date: 2001/04/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Acoustic Signal Processing)
Category: 
Keyword: 
active control,  optimal control,  state feedback,  sound intensity,  finite element method,  

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Summary: 
A new method for active suppression of reflected sound waves is proposed in this paper. The proposed control system is based on the state feedback control. FEM (Finite Element Method) was applied to represent the sound field under the system equations as proposed by Samejima et al. A new performance index was derived so as to minimize the sound intensity leaving a control region, which was set around the control source on a wall. On the basis of the system equations and the new performance index, an optimal feedback law governing suppression of waves reflected from the wall was derived. In order to evaluate the validity of the proposed method, computer simulations in one- and two-dimensional sound fields were executed. In a one-dimensional sound field, the time response was examined, and the distribution of the instantaneous sound intensity was evaluated in a two-dimensional sound field. The results showed that the reflected sound waves can be suppressed quite well in one-dimensional sound fields by using this method and that the proposed method can potentially suppress the reflected sound waves in the two-dimensional sound fields as well.