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.
2.
3.
4.
5.
Amplification
Clear audibility
Volume control
Noise removal
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
REFERENCES
1.Heart Sound Measurement and Analysis System with Digital Stethoscope
Haibin 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
THANK YOU
ANY QUESTIONS..?