摘要
本論文研究目的，是應用時間反轉法根據互易性原理使訊號聚焦於原聲源位置之特性，配合陣列麥克風達到提升訊雜比之功效。同時由於接收訊號包含越多反射訊號，聚焦效果越佳，因此透過增加反射板數量提高抗噪效果，期望於環境噪音明顯之環境下進行產品聲音相關量測之結果，可與無響室中測試結果相近，進而建構一套抗噪量測系統。本文理論部份包含時間反轉理論推導，以及求解環境脈衝響應函數之方法；軟體數值模擬使用聲學分析軟體LMS Virtual.LAB Acoustic，繪製不同形狀、尺寸、與數量的反射板聲音邊界網格並給定點聲源（待測物）和麥克風佈放位置後，計算聲場響應獲得各麥克風之頻域訊號，再匯入Matlab執行反傅立葉轉換並據此求得時域環境脈衝響應函數，模擬時間反轉法的聚焦效果，最後利用相關性係數及訊雜比作為效果量化的指標；實驗部分則根據模擬結果，選擇抗噪效果最佳之反射裝置，於無響室和迴響室中使用陣列麥克風加圓管反射板進行風扇聲源的量測實驗，結果分別可提昇15.53dB與14.12dB，使聲音清晰度和品質大幅提升，明顯抑制環境迴響及雜訊干擾，證明本研究所架構之抗噪量測系統成效。

Abstract
The purpose of this research is to enhance signal-to-noise ratio using microphone array via time reversal method, which lead to focus signal at source location based on reciprocity of wave equation. Furthermore, a new anti-noise measurement system is proposed to obtain similar sound test results of the product whether in anechoic chamber or in noisy environment via increasing the number of reflection plate for better focusing effect produced. The theory part of this thesis includes the derivation of time reversal method and the procedure to obtain environment impulse response function. To complete numerical simulation, a various shape, size, and number of reflection plate were designed and meshed under LMS Virtual. LAB Acoustic. After setting the position of point source and microphones, the frequency domain response of each source-microphone path is calculated and then converted to time domain via Inverse Fast Fourier Transform under Matlab to simulate the process of time reversal method. Finally, the results were quantitated by cross correlation coefficient and signal-to-noise ratio as indicator. Experiments are set according to the simulation configuration with the best anti-noise effect. The measurement tests using circular tube reflection plate and microphone array are conducted in anechoic chamber and reverberant chamber, and the enhancements of signal-to-noise ratio are 15.53dB and 14.12dB respectively. The results show environment reverberation and noise interference are reduced to verify the effect of anti-noise measurement system.

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