ES8405608A1 - Differential stethoscope distinguishing pulse from body noise - Google Patents

Abstract

An electronic unit receives electrical signals from microphone elements (16,18) in respective acoustic heads and directs chosen acoustic signals via a tube to the earpieces (20). The two heads are imposed on widely sepd. parts of the body under examination, and their microphone outputs are applied to individual operational amplifiers (26,28) which are followed by gain adjustment potentiometers (36,40) and a differential amplifier (32). - The component of the output difference signal representing body noise (e.g. respiration) is minimised by adjustment of the potentiometers (36,40), and the distinguishable difference between the two heartbeat signals is amplified (42) for driving an earphone or loudspeaker (44). The differential amplifier (32) is adjusted for min. output noise by means of a balancing potentiometer (46). The signals may be displayed on an oscilloscope connected to output jacks (48-50). (2/3) GBAB- GB2147475 B A portable stethoscope for listening to internal sounds of a body comprising: first and second sensor means for selective application at two selectively and variably spaced portions of the external surface of said body and for detecting said internal sounds and outputting electrical signals in response to said sounds, said sound signal including a first signal desired for detection and a second undesired signal, said first signal being masked by said second signal; comparison means for receiving said electrical signals from said first and second sensor means and outputting a comparison signal, said comparison signal being the difference between concurrently received electrical signals from said first and second sensor means; output means receiving said comparison signal and outputting a sensible signal, said sensible signal corresponding to at least a portion of said difference comparison signal of said detected sound signals.