Abstract: Several techniques are provided for aiding in the discrimination of detected biological signals indicative of blood pressure from detected signals not indicative of blood pressure (e.g., noise). A threshold, based predominantly on a level of noise, is developed and used in the discrimination. A second threshold, based predominantly on levels of previously detected biological signals, is developed and additionally used to help discriminate the biological signals from noise. The biological signals are detected during a selected portion of a cardiac cycle, and additional signals detected outside of the selected portion of the cycle are applied to the detected signals. Another threshold may be developed based predominantly on a level of signals sensed by a transducer positioned to preferentially sense noise; the transducer is positioned so that the noise that it detects is related to noise that is detected during the detection of the biological signals.

Abstract: A stethoscope, operable in an acoustic or electronically augmented mode, is disclosed. In one electronically augmented mode of operation, the stethoscope simultaneously provides the listener with combined unmodified, familiar audible sounds and sounds which have been electronically augmented to bring them within the human auditory range. Additionally, a timing sound may be provided along with the unmodified, familiar audible sounds and electronically augmented sounds to assist the listener in determining when sounds occur in the heart cycle. The timing sound may be enabled in the acoustic mode of stethoscope operation so that the listener can place familiar audible sounds within the heart cycle.

Abstract: A tocodynamometer for providing an electrical output related to body surface displacement of a patient, comprising, a housing, a patient contacting member, a support assembly mounting the member for controlled movement relative to the housing in response to the displacement, and an electro-optical transducer assembly for converting the controlled movement into the electrical output, the transducer assembly comprising relatively movable members one of which is coupled to the patient contacting member for movement therewith to vary the output in response to the controlled movement. In another aspect the support assembly comprises at least one planar spring element having a first portion fixed to the housing and a second portion fixed to the member.