本論文目的是以麥克風陣列的相關技術發展項鍊式助聽器。項鍊式助聽器因穿戴於胸前，所以助聽器可以有較大的體積，方便手指不靈活的長者使用。此項鍊式助聽器系統聲音訊號處理依序可以分為三個階段，分別為麥克風陣列除噪、後濾波 (語音增強)、語音放大與壓縮。本研究分為兩個部分進行，第一個部分為軟體模擬，利用MATLAB模擬各階段的演算法，其中在麥克風陣列除噪階段使用四種不同的自適應方法，選擇除噪效果最優的方法，關閉其語音活動檢測 (Voice activity detection, VAD) 功能與減少自適應濾波器階數，觀察除噪效果的變化，並且結合後濾波，以選擇效果和運算量都適合實現於硬體中的除噪策略；第二個部分為硬體實現，把軟體模擬所決定的除噪策略實現於硬體TMS320C6713開發板中，實際測試除噪策略在硬體運作效果，之後與語音放大壓縮策略整合，並給予六位聽力正常的受測者實際聆聽測試，以檢驗助聽器系統輸出的聲音在實際人耳中的情況，測試結果在SNR為-5dB到20dB的環境下句子平均答對字數都在9個字以上 (滿分為10個字)，主觀評分MOS (Mean opinion score) 的分數也都依序落於3.5到4.6之間 (滿分為5分)，皆有不錯的表現。另外，本研究開發了一個簡易APP (application)，並且把藍牙通訊模組整合入項鍊式助聽器中，使Android裝置可以透過藍牙無線連接更改助聽器中各個頻帶的增益值。經過上述各個研究階段後，完成項鍊式助聽器的原型。;The purpose of this study is to develop a necklace-type hearing aid with related technologies of microphone array. Because the necklace-type hearing aid is worn over the chest, it can be larger in size, which is more convenient for the elderly to use. The signal processing of the proposed necklace-type hearing aid system includes three stages: microphone array noise cancellation, post-filter (speech enhancement), and amplification and compression for speech. This research was divided into two parts. The first part was software simulation, which used MATLAB to implement the algorithms of the three signal processing stages and to verify the actual effects of each stages algorithm. Four different adaptive methods were used in the stage of microphone array noise cancellation, and the method with best performance was selected and combined with a post-filter. Then we observed the result when its voice activity detection (VAD) function was switched off and the number of taps in the adaptive filter was reduced. Finally, the strategy of noise cancellation, which was the combination of the microphone array noise cancellation stage and the post-filter stage, was decided according to the performance and computational complexity suitable for hardware implement. The other part was hardware implementation. The strategy of the best noise cancellation performance determined by simulation was implemented in the hardware TMS320C6713 DSK to verify the performance of noise cancellation in reality. After that, the strategy of amplification and compression for speech is integrated into the hardware with the noise cancellation strategy. Six normal hearing subjects participated the listening test. The test results showed that the average number of correct words in the sentence test was more than 9 words out of 10 words and the score of the subjective MOS (Mean opinion score), which listeners rate between 1.0 and 5.0, were between 3.5 and 4.6 in the environment with SNR from -5dB to 20dB. In addition, a simple Android APP (application) was developed in this research and the Bluetooth communication module was added to the necklace-type hearing aid so that the gain value of frequency bands in the hearing aid can be adjusted by the Android device via Bluetooth wireless connection. After the previous research stages, the prototype of the necklace hearing aid was completed.
