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.[ , ] 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.[ , , , , ] 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.[ , ] 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[ ] (see also [ ] for a list of most recent patents).