聽診器(stethoscope)，為醫生在進行臨床診斷時最重要的工具之一，其優點為以非侵入式的診斷，用作聽取人體內心、肺、胃腸等臟器發出的聲響，進而判斷人體的病症。聽診器自1816年由法國醫生R. Laennec發明以來，到現今經過了將近兩個世紀的演進，從過去早期的鐘式(bell)聽診器到結合麥克風感測元件的電子式聽診器。由於現代電腦科技的發達，近年來電子式聽診器已逐漸發展為電腦化的醫療輔具，透過電腦數位訊號分析的方式，可更快速的協助醫生進行診斷。
以訊號處理系統而言，電子式聽診器內傳遞聲波的部件可視為一聲波感測元件，其本身對於聲波帶有頻率響應特性，會影響量測端訊號的變化，且醫生在進行臨床量測時，容易受到磨擦音和環境噪音的干擾，醫生在進行聽診時可判別其與人體內聲響的差異，但在訊號分析時卻不易分辨，尤其當干擾訊號與病症訊號落在相同的頻帶時，電腦會有誤判的情形，故為了解決此訊號處理上的問題，本研究利用有限元素分析法(Finite element analysis, FEA)之套裝軟體來模擬聽診器的聲波特性，希望能藉此以科學的方式來取得更好的聽診器外形和材料之設計參數。
在模擬驗證的部份，本研究以聲學系統之集總參數模型(lumped-parameter model)為基礎，探討聲波元件的頻率響應變化，並以自製的電腦量測介面，以實物量測的方式測量聽診器實物的頻率響應，驗證軟體模擬的結果。;
The stethoscope is one of the most important tools in clinical diagnosis, owing to its ability in facilitating non-invasive diagnosis from auscultation of internal organs. After nearly two centuries of evolution since being invented by French physician R. Laennec in the year 1816, the stethoscope has changed from the early bell stethoscope to the present electronic stethoscope. Recent technology development further promotes computerized diagnosis from digitalized auscultation signals by way of digital signal processing algorithms. All these progresses lead to a handier tool and more accurate diagnosis by the physicians.
In terms of signal processing systems, electronic stethoscopes can be regarded as a sensing component of acoustic waves. Its acoustic frequency response will affect the measured signals. Moreover, friction and environmental sounds are easily picked up by the stethoscope. These cause the physicians not much difficulty because human can easily distinguish between these interferences and the physiological signal. However, computer programs have not been able to distinguish. To solve this problem, this research uses finite element analysis (FEA) to simulate the acoustic characteristics of stethoscopes, hoping to achieve better stethoscope design parameters in shape and material.
After FEA simulation, lumped-parameter model of the acoustic system is used to explore changes in the frequency response of the acoustic component. In addition, physical measurements are performed with acoustic interface hardware. The FEA simulation is thus verified.
