Stethoscope is a device used for listening to the internal sounds of body (auscultation). It is often used to listen to heart, blood flow, lung and intestine sounds. It is used in conjunction with a sphygmomanometer for blood pressure measurements.
1. Acoustic stethoscope picks up the sound transmission from the chest piece, via air-filled hollow tubes and convey it to the physician’s ears. The chest piece is two sided – a plastic disc (diaphragm) on one side that transmits higher frequency sounds and a hollow cup (bell) on the other that transmits low frequency sounds. The sound level in this type of stethoscope is very low.
2. An electronic stethoscope electronically amplifies low sound levels. Sounds can be recorded through a direct output to an external recording device using electronic stethoscopes.
3. Doppler stethoscope helps auscultate of heart valve movements and blood flow sounds by measuring the Doppler effect of ultrasound waves reflected from the heart. It has an electronic audio output.
4. The heart sounds of unborn infants may be auscultated with fetal stethoscope.