ハウリングキャンセラ機能のある適応制御アクティブノイズコントロールの騒音低減効果に関する考察 : 2本マイク伝達関数比法の効果

概要

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The authors have studied a howling canceler system for active noise control in a duct. The effect of howling canceler employing an echo canceler or two kinds of 2-microphone systems (one is a 2-Microphone delay system and the other is a 2-Microphone transfer function ratio system) was confirmed from the viewpoint of eliminating the sound pressure signal from the secondary source. In this paper, the noise reduction effect of the adaptive control system utilizing this howling canceler, particularly utilizing the 2-Microphone transfer function ratio system, is examined. A filtered-X algorithm was used, because an acoustical transfer function from the secondary source to the evaluation microphone exists. A problem in applying the adaptive control system was identified : occurrence of an overflow phenomenon of the discrete system in the low frequency range because of the low efficiency of the speaker in this range. In this case, the high-pass filter effect of the 2-Microphone howling canceler system was useful for achieving stable control. This result is introduced theoretically and confirmed experimentally. The adaptive active noise control system with howling canceler was applied to axial fan noise. A good noise reduction effect was obtained.
社団法人日本機械学会の論文
1994-01-25