Electric “Ear” Helps Photograph Heart Beats (Jun, 1934)
Electric “Ear” Helps Photograph Heart Beats
Photographic records of pulsations of the human heart are produced by a portable instrument containing an electric “ear” and equipment for converting sound into light. The electric ear, a sensitive condenser microphone, picks up the heart’s sounds, which are amplified until they can be heard through a radio loud speaker. The amplified sounds are converted into a vibrating light beam which is focused on a rapidly moving strip of photographic paper. At the same time, the light is projected on a ground glass screen on the control panel of the instrument, so that the light variations may be watched by the operator. Earphones enable the operator to hear the sounds at the same time. The strip of sensitized paper records the light any defect in operation of valves or muscles, measure comparative intensity of the different sounds of the heart beat, time the pulse and obtain other valuable information. The apparatus is contained in a case eight inches wide, twelve inches high and twenty-one inches long. It weighs less than thirty-eight pounds. The machine operates on 110-volt house current.