摘 要

腹部聽診是非侵入式而且簡單的臨床檢查腸胃疾病方法，由於醫師無法長時間，對同一病人做腸音的聽診，因此我們發展一套利用可攜式個人電腦之腸音分析系統，本系統主要利用適應性濾波器消除大部份雜音後，再利用CoBliSS (Convolutive Blind Source Separation )演算法，將腸音信號有效分離出來。

腸音的萃取系統分為類比的放大濾波與數位的訊號處理。其中,類比電路部分包含有麥克風,前置放大器,帶通濾波器與後級微調。應用類比/數位 轉換器截取訊號至電腦中，利用Labview發展之適應性濾波器即時的濾除環境噪音，再以離線方式利用Matlab發展之CoBliSS演算法將腸音萃取出來。

測試結果顯示,本腸音訊號萃取系統確實可以把頻率約為50~150Hz之心音濾除掉。外界雜訊的干擾也能夠經由適應性濾波器的處理而得到明顯的降低。CoBliSS (Convolutive Blind Source Separation )演算法可有效的萃取出腸音。最後期望本研究結果能提供臨床醫師診斷的參考依據及腸音的研究。

Abstract

The auscultation of the abdomen is a noninvasive and simple way to provide the clinical diagnosis reference for gastrointestinal disease. However, auscultation is a time consuming and subjective work. Therefore, it is needful to develop a computer-aided bowel sound monitoring system. In this study, an adaptive filter was designed to reduce the environmental interference, then the CoBliSS ( Convolutive Blind Signal Separation) algorithm was employed to extract the pure bowel sound.

The bowel sound mornitoring system includes analog hardware and digital signal processing algorithm. The analog hardware is composed of microphone, pre-amplifier, band-pass filter and post-amplifier circuit. The bowel sound signal passed through an analog circuit, then through an Analog/Digital converter stored in PC for off-line processing. An adaptive filter algorithm based on Labview environment was used to reduce environmental interference. The CoBliSS algorithm developed on Matlab Signal tool box was used to extract the bowel sound from two different sound sources.

The results show that the heart sound (50~150 Hz) is easily eliminated through the band-pass filter, the environmental interference is effectively reduced by the adaptive filter algorithm, and the CoBliSS algorithm extracts the bowel sound efficiently. We hope that this system can be used in clinical applications.

[1] M. Sugrue and M. Redfern , ”Computerized phonoe-nterography : The clinical investigation of a new system,” Journal of Clinical Gastroenterology, vol. 18, no. 2, pp. 139-144,1994.
[2] H. Yoshino, Y. Abe, T. Yoshino, and K. Ohsato, ”Clinical application of spectral analysis of bowel sounds in intestinal obstruction,” Diseases of the Colon and Rectum, vol.33, no. 9, pp. 753-757,1990.
[3] H. A. Mansy and R. H. Sandler, ”Bowel-Sound Signal Enhancement Using Adaptive Filtering,” IEEE Engineering In Medicine And Biology, pp. 105-117, 1997.
[4] D. W. E. Schobben and P. C. W Sommen, ”Realtime Realization Aspects of the CoBLiss Blind Signal Separation Algorithm”.
[5] P. He , P. C. W. Sommen and B. Yin, ”A Real-time DSP Blind Signal Separation Experimental System Based on a New Simplified Mixing Model,” Proceeding of the IASTED International Conference on Signal and Image Processing, 1998.
[6] B. Widrow, ” Adaptive noise cancelling: Principles and applications, ” IEEE, vol. 63, no.12, pp. 1692-1726,1975.
[7] V. K. ingle, J. G. Proakis, Digital Signal Processing Using Matlab, Books/cole,2000.
[8] Labview Basics I course Manual, National instrument,2000.
[9] Leontios j.Hadjileontiadis, ”Enhancement of Bowel Sound by wavelet-Based Filtering,” IEEE Transactions on Biomedical Engineering ,vol. 47,no. 7, 2000.
[10] N. V. Thakor , ”Applications of adaptive filtering to ECG
analysis: Noise cancellation and arrhythmia detection,” IEEE
Transactions on Biomedical Engineering, vol.38, no. 8, pp.785-
794,1991.
[11] J. Chen and J. Vandewalle, ”Multichannel adaptive enhancement
of the electrogastrogram,” IEEE Transactions on Biomedical
Engineering, vol. 37, no. 3, pp.285-294,1990.
[12] L. J. Hadjileontiadis and S. M. Panas ”On modeling impulsive
bioacoustic signals with symmetric astable distrubutions:
Application in discontinuous adventitious lung sounds and
explosive bowel sounds,” Engineering in Medicine and Biology
Society, vol. 1, pp. 13-16,1998.
[13] M. N. Elaine and M. Jon , Human anatomy, Benjain,1996.
[14] A. J. Vander , Human physiology, McGraw-Hill,1994.
[15] 沈清良,實用解部學,華杏,1996
[16] 陳志超, ”腸音偵測系統之建立 ” ,成大學醫工所,碩士論文，
1999.
[17] 陳啟鐘, “建立即時腸音偵測系統“, 成大學醫工所, 碩士論文,
2001.
[18] 蘇奕肇,精選類比實用電路集,全華科技圖書股份有限公司,1997.