D EVELOPMENT OF A D IGITAL A USCULTATION D EVICE FOR REAL TIME M URMUR D ETECTION Tanvi Kalra 1, Abhinav 2 and Sneh Anand 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. Amplification 2. Clear audibility 3. Volume control 4. Noise removal 5. 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 – 2 nd 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

F EATURES & B ENEFITS  Varying gain  AUDACITY (compatible)  Beneficial device for cardiologists  Easily diagnose HEART’s conditions

S NAPSHOT OF THE AUSCULTATION Figure 3: heart sounds of healthy and unhealthy subjects

REFERENCES 1.Heart Sound Measurement and Analysis System with Digital StethoscopeHeart Sound Measurement and Analysis System with Digital Stethoscope Haibin Wang; Jian Chen; Yuliang Hu; Zhongwei Jiang; Choi Samjin; Biomedical Engineering and Informatics, BMEI '09.Biomedical Engineering and Informatics, BMEI '09. 2nd International Conference on 2nd International Conference on Digital Object Identifier: /BMEI /BMEI Publication Year: 2009, Page(s): The embedded digital stethoscope uses the adaptive noise cancellation filter and the type I Chebyshev IIR bandpass filterThe 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 to reduce the noise of the heart sound Ying-Wen Bai; Chao-Lin Lu; Enterprise networking and Computing in HealthcareEnterprise networking and Computing in Healthcare Industry, HEALTHCOM Proceedings of 7th International Workshop on Publication Year: 2005, Page(s): Design and implementation of a remote embedded DSP stethoscope with a method for judging heart murmurDesign 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, I2MTC '09. IEEE Digital Object Identifier: /IMTC Publication Year: 2009, Page(s): Instrumentation and Measurement Technology Conference, I2MTC '09. IEEE /IMTC Segmentation of heart sound recordings from an electronic stethoscope by a duration dependent Hidden-Markov ModelSegmentation 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:Computers in Cardiology, /CIC /CIC Publication Year: 2008, Page(s): Analysis and classification of heart sounds and murmurs based on the instantaneous energy and frequency estimationsAnalysis 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 Proceedings Volume: 2TENCON Proceedings Digital Object Identifier: /TENCON Publication Year: 2000, Page(s): vol /TENCON Recursive least squares adaptive noise cancellation filtering for heart sound reduction in lung sounds recordingsRecursive 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, Proceedings of theEngineering in Medicine and Biology Society, Proceedings of the 25th Annual International Conference of the IEEE 25th Annual International Conference of the IEEE Volume: 3 Digital Object Identifier: /IEMBS Publication Year: 2003, Page(s): Vol /IEMBS

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