適応信号処理によるアクティブ吸音装置

概要

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An active absorber of sound using an adaptive algorithm is studied. To realize an active sound absorber, the incident wave on the absorber which is usually mixed with the reflected wave, must be known. In conventional methods, in order to separate the incident wave from the reflected wave using two microphones, the delay time during which the sound propagates between the two microphones must be precisely known and the two microphones must have exactly the same sensitivity. We propose two methods using adaptive processing, which do not require such preprocessing for extracting the incident wave : an off-line method using an impulse as a learning signal and an on-line method using sound intensity control. The off-line method, in which the optimum conditions are learned efficiently, yields sound absorption coefficients of more than 99% at low frequencies. In the on-line method, which do not require such learning signals as the off-line method, sound absorption coefficients of more than 95% can be realized at low frequencies.
社団法人日本音響学会の論文