A multi-channel phonocardiogram record-analyze system based on Fourier optics



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The phonocardiogram (PCG), the acoustic signal at the precordium generated by vibrations of the cardiovascular system, during Its operation, Is one of the diagnostic parameters that lends Itself to a noninvasive type analysis of cardiac condition. This paper describes a multi-channel PCG machine that directly records the phonocardiographic signal In the form required for Fourier-optical analysis. The format of the recording is a time record In which density variations of Individual tracks of low contrast 35 millimeter photographic film represent a corresponding physiological signal. A four microphone array, located on the subject's chestwall, provides an Information pattern varying In space, as well as time. In Itself, without subsequent analysis, this pattern Is a valuable record of the acoustic correlates of cardiac activity. In this work, use was made of an available electro- optical system to perform Fourier-optical analysis of the multi-PCG record. With the aid of pattern-recognition and decision-making apparatus In the analysis system, the record-analyze system appears to be adaptable to automatic differentiation between: (a) normal PCG records, (b) normal PCG records with functional murmurs and (c) PCG records with organic or pathological murmurs.