摘要
聲場回授（acoustic feedback）是管道主動式噪音控制（ANC）實務應用中常發生的問題，會造成控制系統的不穩定性。本文根據管道聲場的平面波傳遞理論，與聲場的轉移函數，發展出消除聲場回授影響的理論方程式，並應用快速傅立葉轉換技術在頻率域中進行演算法的計算，由參考輸入麥克風與誤差麥克風感測的訊號中分離出原始主要噪音的訊號。本文研究採用LabVIEW圖控程式來實現演算法，實驗結果顯示本文所使用的方法，確實能分離出不受聲場回授干擾的原始主要噪音訊號。在管道噪音主動控制的實務應用中，將適應性控制理論或是其他控制方法結合本文研究的成果，可以有效改善控制不穩定的問題。
並列摘要
In most practical applications of active noise control, the acoustic feedback is a major problem that often interferes with the operation of the control system and even renders it unstable. The theoretical equations that reduce the influence of acoustic feedback are developed based on plane wave transmission theory and transfer function of sound in a duct. The original signal of primary noise is separated from the measured signals of reference microphone and error microphone which are transformed to frequency domain by FFT and operated. In this study, we use LabVIEW programming language to carry out the algorithm. The results showed that the proposed method can effectively reduce the influence of acoustic feedback. In practical application of active noise control in a duct, the adaptive control or other control method incorporate the proposed method in this paper will improve the stability and performance effectively.
延伸閱讀
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