Implementation of Active Noise Control on the Headphone

耳機之主動控制實現

陳國在 ； 周俊宏 ； 陳志煌

《中華民國音響學刊》 13期 (2008/11) Pp. 1-15

https://doi.org/10.30049/JASRC.200811.0001

摘要

本文利用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600 Hz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10~20 dB的消音效果。另外，雙邊耳機消音實驗中，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差異。其中，單頻部分300 Hz，400 Hz及500 Hz右耳和左耳控制後的音壓位準差值大約在5~8 dB。

關鍵字

主動噪音控制 ； 有限脈衝響應 ； 耳機

並列摘要

This article utilizes the FIR (Finite Impulse Response) digital filter as the main structure of the control system and uses 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 600 Hz and the noise sources to be adaptively controlled include those ones dealing with mono, dual, and white noise sources. The experiment of the study is firstly to try to attenuate the sound at the unilateral headphone, the result of noise reduction by 10~20 dB 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 are quite different, and so did the resulting noise reductions. Therefore, the distinction of control effectiveness by 5~8 dB between two ears is obtained.

並列關鍵字

Active Noise Control ； Finite Impulse Response ； Headphone