DEVELOPMENT OF A DIGITAL AUSCULTATION DEVICE FOR REAL TIME

MURMUR DETECTION

Tanvi Kalra1, Abhinav2 and Sneh Anand2

 

1 - Department of Biomedical Engineering, Rayat & Bahra Institute of Engineering & Bio-Technology, Punjab

2 - Centre for Biomedical Engineering, Indian Institute of Technology – Delhi

NEED OF THE SYSTEM Training required – detection of subtle heart sounds Ambient noise in the hospital Reliable diagnosis Portable device

INTRODUCTION development of a digital auscultation device second order butterworth filter reduce the ambient noise integration of 1. traditional stethoscope 2. an electret microphone 3. an amplifier circuit software - audacity real time plotting detection of murmurs diagnosing of heart sounds battery powered

FEATURES

1. Amplification2. Clear audibility3. Volume control4. Noise removal5. Real time plotting

BLOCK DIAGRAM

Figure 1: block diagram of the digital auscultation device

CONNECTIONS

Figure 2: (a) – traditional stethoscope, (b) – hardware circuit,(c) – compatible earphones, (d) – connecting cable, (e) – plotted heart sounds.

HARDWARE Electret microphone – frequency response (30 Hz - 10 KHz) Amplifier circuit – linear op-amps - gain (20) Buffers – removing the loading effects. Filters – 2nd order butterworth band pass filter - frequency range (50 Hz – 600 Hz) - diaphragm mode Output – potentiometers (volume and gain control) 1. Jack 1 – Audible signal 2. Jack 2 – Plotted signal

FEATURES & BENEFITS Varying gain AUDACITY (compatible) Beneficial device for cardiologists Easily diagnose HEART’s conditions

SNAPSHOT OF THE AUSCULTATION

 Figure 3: heart sounds of healthy and unhealthy subjects

REFERENCES1.Heart Sound Measurement and Analysis System with Digital StethoscopeHaibin Wang; Jian Chen; Yuliang Hu; Zhongwei Jiang; Choi Samjin; Biomedical Engineering and Informatics, 2009. BMEI '09. 2nd International Conference on Digital Object Identifier: 10.1109/BMEI.2009.5305287 Publication Year: 2009 , Page(s): 1 - 5 2. The embedded digital stethoscope uses the adaptive noise cancellation filter and the type I Chebyshev IIR bandpass filter to reduce the noise of the heart sound Ying-Wen Bai; Chao-Lin Lu; Enterprise networking and Computing in Healthcare Industry, 2005. HEALTHCOM 2005. Proceedings of 7th International Workshop on Publication Year: 2005 , Page(s): 278 - 281 3. Design and implementation of a remote embedded DSP stethoscope with a method for judging heart murmur Ying-Wen Bai; Cheng-Hsiang Yeh; Instrumentation and Measurement Technology Conference, 2009. I2MTC '09. IEEE Digital Object Identifier: 10.1109/IMTC.2009.5168706 Publication Year: 2009 , Page(s): 1580 - 1585 4. Segmentation of heart sound recordings from an electronic stethoscope by a duration dependent Hidden-Markov Model Schmidt, S.E.; Toft, E.; Holst-Hansen, C.; Graff, C.; Struijk, J.J.; Computers in Cardiology, 2008 Digital Object Identifier: 10.1109/CIC.2008.4749049 Publication Year: 2008 , Page(s): 345 - 348 5. Analysis and classification of heart sounds and murmurs based on the instantaneous energy and frequency estimations Sharif, Z.; Zainal, M.S.; Sha'ameri, A.Z.; Salleh, S.H.S.; TENCON 2000. Proceedings Volume: 2 Digital Object Identifier: 10.1109/TENCON.2000.888404 Publication Year: 2000 , Page(s): 130 - 134 vol.2 6.Recursive least squares adaptive noise cancellation filtering for heart sound reduction in lung sounds recordings Gnitecki, J.; Moussavi, Z.; Pasterkamp, H.; Engineering in Medicine and Biology Society, 2003. Proceedings of the 25th Annual International Conference of the IEEE Volume: 3 Digital Object Identifier: 10.1109/IEMBS.2003.1280403 Publication Year: 2003 , Page(s): 2416 - 2419 Vol.3

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