Abstract: A portable apparatus for determining the degree of occlusion in a blood vessel. The apparatus includes a transmitter for producing an ultrasonic signal, a first probe for directing the ultrasonic signal to a first location in a blood vessel and a second probe for directing an ultrasonic signal to a second location in the blood vessel. A first receiver receives the ultrasonic signal after return from contact of blood flowing in the blood vessel at the first location and produces a first received signal representative thereof. A second receiver receives the ultrasonic signal after returning from contact with blood vessel at the second location and produces a second received signal representative thereof. A difference measuring circuit receives the first and second received signals and produces a difference signal representative of the difference between the first and second received signals so that a difference in blood flow velocity at the first and second locations can be determined.

Abstract: A computerized audiometer is provided with at least one head set, a control switch, a tone generator for providing a plurality of sequential tones of different frequencies and amplifications to at least one head set, and a central processing unit for receiving data representative of the response to the test of the person being tested as reflected by the operation of the control switch. The central processing unit is adapted to analyze the test data and produce a program representative of the correction required by the person being tested. The audiometer is provided with a programming output adapted for coupling to a hearing aid for programming a hearing aid by applying the program developed by the central processing unit to the hearing aid.

Abstract: An electrocardiograph included microprocessor control of signals not only from conventional electrocardiograph electrodes but also from a phonocardiographic pickup. The signals are multiplexed, converted to digital representations for processing and are displayed on a printer. Keyboard control of the microprocessor and both analog signal and modem outputs are provided.

Abstract: A portable differential stethoscope includes small microphone elements which are attached to the stethoscope heads to pick up acoustic signals from the body. The sounds picked up by the stethoscope heads include body noise signals as well as heartbeat signals. Each stethoscope head and microphone element provides an output which is amplified in an individual amplifier. The two amplified signals are inputted to separate terminals of a differential amplifier through a gain and balance control element. The differential amplifier outputs a difference signal which is amplified and inputted to an electrical headset or an electrical earphone element which is acoustically coupled to the conventional acoustic tube.