離散噪音分析與控制

Abstract

為了降低環境中的噪音今日已有許多的主動式噪音控制技術被發展與探討，包括各種的類比式或數位式控制器設計，以噪音回饋的方式來說又可以分為前饋控制式（feed-forward control）與反饋控制式（feedback control）兩大類；事實上許多相關的研究與應用報告都指出每一種控制方式在實際的使用經驗上都有其個別的優點與缺點，沒有一種控制方式或架構可以適應所有的噪音消除狀況。本論 文首先探討聲波干涉的物理與音壓降低的關係，接著了解一般常見適應性tap濾波器的主動噪音消除方法，進而提出一個針對離散噪音控制的主要噪音成分合成的控制方法；最後透過Matlab進行離散噪音的控制模擬，顯示出主要噪音成分合成的控制方法於離散噪音控制上確實有良好的效果。

In order to reduce the environment noise, there are several ANC technologies developed and discussed today；A variety of analog and digital ANC systems could be divided into feed-forward and feedback control types by its feedback method. According to lots of researches and application reports show that each control method has its advantages and drawbacks depending on the applied situation. There is no control method or structure suits for all kinds of noise cancelling status. In this paper we discuss the relation between sound wave interference and sound pressure reduction at the beginning. And understand the adaptive filtering method for general ANC systems. Then we propose a noise control method for discrete frequency noise by synthesizing its major components . Finally, it proves a nice noise reduction in discrete frequency noise control by Matlab simulation.