摘要
摘 要 本文所研究之主動式降噪安全帽(Helmet)是以採用主動噪音控制(Active Noise Control, ANC)的理論為基礎，以產生與環境噪音之反噪音聲波來消除環境噪音；尤於科技的進步帶來了生活便利，在交通工具與工業上的環境噪音，更是不可避免的環境噪音對於人體身心造成傷害。主動式降噪安全帽(Helmet)目前在使用頻率上並不普遍，主要因為造價費用上相當高，目前只用在航空業上，使用主動式降噪安全帽(Helmet)來保護航空站的人員。對於主動噪音控制(ANC)降噪的概念應用已愈來愈廣泛，並且數位信號處理上都是使用數位信號處理器(Digital Signal Processor, DSP)作為平台居多，因為DSP具有強大的資料處理能力和高運算速度，使ANC在即時資料運算變得容易實現。但是，除了DSP能完成ANC系統外，本文將實驗以單晶片微控制器(Micro-controller Unit, MCU)來取代MCU-DSP，優點在於不到1/6的價格。在演算法上是採用Feedback FXLMS架構，不需使用參考麥克風(Reference Microphone)只需要誤差麥克風(Error Microphone)的優點，因此誤差麥克風(Error Microphone)的位置在聲場頻率響應相當重要，關係到第二路徑(Secondary Path)的估測與降噪時收斂的品質，使MCU設計的ANC安全帽有更好的降噪能力。由實驗結果可知本文在降噪能力上可消除低頻噪音達8dB以上，在錄製摩托車騎乘之噪音有5dB的降噪效果。
並列摘要
Abstract The topic for this research is “Active Reduce Noise Control Helmet,” this idea is basic on “Active Noise Control,” which means can avoid or keep away the acoustic from the noisy environments. In particular, advances in technology to facilitate life there are much noise pollution surrounding in transportation vehicle and industry-wide environments’. It is inevitable that noise pollution will affect our physical and psychological harm. The “Active Reduce Noise Control Helmet” is not public to use, because it is costly, currently use in aviation to protect the people who works in this area; The idea of “Active Reduce Noise Control Helmet,” is become increasingly in everywhere; and also the digital signal process this idea is useful in Digital Signal Processor (DSP) platform, it is because DSP has a powerful data processing capability and high operation speed, so that can make ANC do real-time data operations to make it easier to achieve. However not only DSP can be achieve to ANC, in this practical research will use Micro-Controller Unit (MCU) instead MCU-DSP, the advantage will less than one-sixth of the price. In algorithm does not use Reference microphone but use Error microphone and it is used in the framework Feedback FXLMS; So, the Error microphone location’s sound-field frequency response is really important, it will affect Secondary path’s calculate and noise reduction collection quality, then make MCU designer have better noise reduction quality. In conclusion will known the noise reduction ability will eliminate low-frequency noise over than 8dB, and motorcycle riding in the recording of the noise, there is 5dB noise reduction.