Instrumentation for Spectral Phonocardiography

The development stages of the instrumentation system for displaying the three dimensions of heart sounds, time, frequency and intensity are described. The heart sounds and physiological data are recorded on magnetic tape. The tape information is repetitively played back, filtered and presented as intensity modulation on cathode-ray tubes having a slow TV type raster where the horizontal sweep represents time in the cardiac cycle and the vertical represents frequency. The resulting patterns which are photographed and visually monitored are used for research, teaching and diagnosis.