主動式噪音控制–應用於鼾聲消除

Application of Active Noise Control for Reducing Snore

廖國鈞(Kuo-Chun Liao)

指導教授 ： 張政元

中原大學/工學院/電機工程研究所/碩士(2011年)

https://doi.org/10.6840/cycu201100541

摘要

本篇論文討論的是將主動式噪音控制方法實現在數位訊號處理器中進行鼾聲訊號的消除。一般來說，在日常生活中鼾聲是一個很常見且很嚴重的一個問題。鼾聲的噪音量有時可以高達90dB，不只造成室友的聽力損害也會干擾室友的睡眠品質造成白天顯得睡眠不足的現象，甚至造成白天工作沒效率以及開車時因嗜睡導致安全問題等等。大部分的解決鼾聲方法中，都是使用被動式的器材進行鼾聲噪音的阻隔，譬如使用耳罩或者耳塞，可是這種產品對於睡眠者來說戴著睡眠是不舒服的。其他方法中也有使用止鼾枕頭和止鼾牙套但這些一樣對睡眠者來說會造成不舒服的感覺。對於一個鼾聲的特性來說。鼾聲是一種週期性的聲音，而鼾聲可以被分為吸氣與吐氣兩個部分。鼾聲的主要頻率是在100~300Hz之間。根據聲音疊加原理，使用主動式噪音控制系統產生人工的反鼾聲噪音進行鼾聲消除是比較好的方式。
本篇論文中，所使用的主動式噪音控制演算法是filtered-x least mean square演算法，對於欲消除的鼾聲噪音訊號產生相對的反鼾聲訊號進行消除。藉由使用數位訊號處理器晶片，針對系統的二路徑進行估測(從次級喇把至誤差麥克風這段系統響應)，將誤差訊號由麥克風量測後回授回系統中進行適應性FIR濾波器進行權重的調整，並產生反鼾聲噪音。這個人工的反鼾聲訊號振福與噪音相同，但相位與鼾聲訊號相差180°。因此，反鼾聲訊號會在聲場中與鼾聲訊號進行干涉與相互抵消，並且在睡眠者雙耳的周圍產生一個靜音區以提高睡眠品質。

關鍵字

數位訊號處理器DSP ； Multi-channel FXLMS ； 主動鼾聲控制系統 ； 主動噪音控制

並列摘要

This thesis discusses the cancellation of a low frequency snore signal by using ANC based method in a DSP. Generally speaking, snoring is a high up problem in nowadays. The volume of severe snoring can reach up to 90 dB, which not only cause hearing loss but also disturb the sleep of bed partner. It also linked to extremely sleepiness in daytime of snorer and his bed partner, leading to the loss of productivity in the work, safety of driving and occupation. Most solutions to this problem use passive earmuffs or earplug for the bed partner. But these facilities are uncomfortable to be wear when sleep. Another method like anti-snore pillow or tooth socket for the snorer is uncomfortable, either. A period of snore can be divided into two components, inspiration and expiration. The frequency of snore is also in low frequency, between 100 to 300 Hz. Accordingly based on the theory of superposition, the ANC system is a better way to reduce the snore noise by generating an artificial anti-snore signal
This thesis uses the popular filtered-X least mean square (FXLMS) method in ANC to derive the proper signal to cancel the undesired snore noise. By using a DSP chip, this method can be realized through the estimation of secondary path, from the location of secondary speaker to the error microphone, and then tune the weights of the FIR filter to generate the anti-snore noise. This artificial noise has the same magnitude and 180 degrees phase shift of the annoying snore. Therefore, the anti-snore noises can interference the snore signal, producing a silent zone at the ears of bed partner.

並列關鍵字

FIR ； LMS ； snore cancellation ； DSP

參考文獻

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