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Clinical Comparison of Acoustic and Electronic Stethoscopes and Design of a New Electronic Stethoscope

      The stethoscope is one of the most simple and practical diagnostic tools used in medicine.[
      • Tavel ME
      Cardiac auscultation A glorius past—but does it have a future?.
      ,
      • Tilkian AG
      • Boudreau
      • Conover M
      ] Presently, 2 different types of stethoscopes are available on the market: acoustic and electronic. The main advantages of acoustic stethoscopes are their robustness and ergonomic designs. However, they are not ideal because they attenuate sound transmission proportional to frequency, their frequency response shows maxima and minima at very specific frequencies due to tubular resonance effects, and differences in the transmission properties are observed between different models.[
      • Abella M
      • Formolo J
      • Penney DG
      Comparison of the acoustic properties of six popular stethoscopes.
      ,
      • Charbonneau G
      • Sudraud M
      Mesure de la réponse en fréquence de quelques stéthoscopes usuels Conséquences pour l’auscultation cardiaque et pulmonaire.
      ,
      • Ertel PY
      • Lawrence M
      • Song W
      How to test stethoscope?.
      ,
      • Gavish B
      • Heller O
      A practical method for evaluating stethoscopes.
      ,
      • Kindig JR
      • Beeson TP
      • Campbell RW
      • Andries F
      • Trave ME
      Acoustical performance of the stethoscope a comparative analysis.
      ] Because the intensity of heart sounds and murmurs is generally faint with some sounds below the threshold of hearing, amplification of the acoustic signal with a more uniform frequency response has been introduced in electronic stethoscopes to solve the main limitations of acoustic stethoscopes.[
      • Dowell LA
      • Fant GE
      • Watkins WD
      Design and construction of an electronic stethoscope.
      ,
      • Philip JH
      • Raemer DB
      An electronic stethoscope is judged better than conventional stethoscopes for anesthesia monitoring.
      ] However, it appears that these advantages are overcome by the sensitivity of the electronic stethoscope to manipulation artifacts, and electronic and ambient noises. Also, they do not take into consideration the sensitivity of the human ear, which varies significantly as a function of frequency. Consequently, the acoustic stethoscope is still the one mostly used today, even if several sophisticated designs have been patented for the construction of electronic stethoscopes during the last 20 years[

      Bredesen MS, Schmerler ED. Intelligent stethoscope. Patent Number: 5,010,889, 1991.

      ] (see also [

      Durand J, Durand LG, Grenier MC. Electronic stethoscope. Patent Number: 5,602,924, 1997.

      ] for a list of most recent patents).
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      References

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        Cardiac auscultation.
        Circulation. 1996; 93: 1250-1253
        • Tilkian AG
        • Boudreau
        • Conover M
        Understanding Heart Sounds and Murmurs with an Introduction to Lung Sounds. W.B. Saunders Company, Philadelphia1984: 1-265
        • Abella M
        • Formolo J
        • Penney DG
        Comparison of the acoustic properties of six popular stethoscopes.
        J Acoust Soc Am. 1992; 91: 2224-2228
        • Charbonneau G
        • Sudraud M
        Mesure de la réponse en fréquence de quelques stéthoscopes usuels.
        Bull Europ Physiopathol Respir. 1985; 21: 49-54
        • Ertel PY
        • Lawrence M
        • Song W
        How to test stethoscope?.
        J Appl Physiol. 1983; 54: 714-719
        • Gavish B
        • Heller O
        A practical method for evaluating stethoscopes.
        Biomed Instrum Technol. 1992; : 97-102
        • Kindig JR
        • Beeson TP
        • Campbell RW
        • Andries F
        • Trave ME
        Acoustical performance of the stethoscope.
        Am Heart J. 1982; 104: 269-275
        • Dowell LA
        • Fant GE
        • Watkins WD
        Design and construction of an electronic stethoscope.
        Clin Eng. 1988; 5: 355-357
        • Philip JH
        • Raemer DB
        An electronic stethoscope is judged better than conventional stethoscopes for anesthesia monitoring.
        J Clin Monit. 1986; 2: 151-154
      1. Bredesen MS, Schmerler ED. Intelligent stethoscope. Patent Number: 5,010,889, 1991.

      2. Durand J, Durand LG, Grenier MC. Electronic stethoscope. Patent Number: 5,602,924, 1997.

      3. Savage G and Swift M. Headset for electronic stethoscope. Patent Number: 5,561,275, 1996.