人體組織中，不同的器官構造有其不同的功能來維持人體的正常運作，心臟和肺臟就是相當重要的兩個器官。心臟和肺臟在運作過程中有其特殊的心音和肺音，也有其不同的聲音頻率範圍。而當有心臟或肺臟有異常症狀的時候，其心音和肺音也會有異常聲音，而這異常聲音也往往是醫師診斷病人的重要依據之一。 本研究在於製作一電子式聽診器，除了能聽到心音和肺音之外，更將兩種聲音由電腦顯示出心音圖和肺音圖。首先由電容式麥克風將聲能轉成電能，經過放大電路和濾波電路，使欲擷取的聲音頻率範圍通過後，可透過喇叭直接聽取聲音，減少醫師戴上傳統耳栓式聽診器造成耳朵酸痛。其中在放大電路中加上了自動準位調整的回授電路，目的在於避免當有較大能量的異常肺音而可能造成的飽和輸出電壓。除了透過喇叭直接聽取聲音之外，另外經過放大和濾波後的心肺音訊號，使其經過平移電路，將輸出電壓範圍固定在0 V到5 V內，接著以微處理器dsPIC30F2010執行類比數位轉換，經由RS232傳輸到電腦端接收，以軟體LabVIEW顯示心音圖和肺音圖，作為醫師診斷病人的另一項重要輔助工具。 本研究亦對本系統作了詳細的測試研究，確保成果能符合本研究最初之所求。 A Prototype of Digital Stethoscopes Abstract Heart and lung have their own special functions to make human body work normally. The two organs have their own sounds when they function normally or abnormally. Doctors can use the two useful tools to diagnose patients exactly. The purpose of the study is to build a model of electrical stethoscope. Beside to hear the heart sound and lung sound directly by speakers, it could also show the phonocardiogram and phonopneumogram waveforms in the computer. First, it makes the sound wave to become the electrical potential by the electrical microphone. After the amplification circuit and filtering circuit, it can hear the sounds what we want by the speaker. The system adds an auto level control (ALC) feedback circuit in the amplification circuit to avoid the output saturated voltage. To make the signals that pass through the amplification and filtering circuits pass through the shift circuit will have a positive output that ranges from 0 V to 5 V. After that, the microprocessor dsPIC30F2010 makes the analog data to become the digital data. That is analog to digital converter (ADC). It uses the RS232 transmission line to pass the digital data to the receive point computer. In the end, the system shows the phonocardiogram and phonopneumogram waveforms by LabVIEW. The waveforms could help doctors to diagnose patients. Finally, the study tests every part of the system to make sure the exactness. And the result conforms what the study wants.
