耳機之主動控制實現

Implementation of Active Noise Control on the Headphone

陳志煌(Zhi-Huang Chen)

指導教授 ： 陳國在

國立臺灣大學/工學院/工程科學及海洋工程學研究所/碩士(2008年)

https://doi.org/10.6342/NTU.2008.10186

摘要

本論文利用FIR(Finite Impulse Response)數位濾波器，作為本論文之控制系統的主體架構，並以LMS(Least Mean Square )演算法來即時修正數位濾波器之係數，以求得最佳的控制效果。
在實驗方面， 控制的頻率範圍在600hz以下，適應性主動控制針對不同的噪音源(單頻，雙頻及白噪音)進行消音控制，此實驗起初是針對單邊耳機來進行消音，在單頻，雙頻及窄頻部分皆有10~20dB的消音效果。接著，再著手雙邊耳機消音，因為聲波到達右耳和左耳存在時間差，因此兩支麥克風量到的聲音壓力不相同，最終導致控制後的結果也不盡相同，其中在單頻部分f=300Hz,400Hz,及500Hz右耳和左耳控制後的音壓位準差值大約在5~8dB。

關鍵字

適應性控制

並列摘要

It is to utilize FIR (Finite Impulse Response) Digital filter as the main structure of the control system for this thesis,and meanwhile use LMS (Least Mean Square ) to modify
in real time weighting coefficient of the algorithm to feedback the digital filter for trying to get the best control effectiveness.
As regard to the experiment, the frequencies under control
are all below 600Hz and the adapatively active control of acoustic sources .including these ones for mono,dual,and white noise sources on the sound reduction to be controlled.The experiment of the study is firstly to try to attenuate the sound at the unilateral headphone,the result of noise reduction by 10~20dB for mono,dual,and white noises are obtained .
Then,we continue to set up the active attenuation on the bilateral headphone.Due to the different travel times for sound waves to arrive the right and the left ears,the sound pressures measured at the associated microphones,and so did the resulting noise reductions.Therefore,the distinction of controll effectiveness by 5~8dB between two ears is obtained.

並列關鍵字

adaptive control

參考文獻

[23] 蕭俊祥、盧士一,“以數位訊號處理器實現之主動式耳機開

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