Time frequency analysis of canine heart sounds

Six different time frequency distributions (TFDs) have been used to analyze the first and second heart sounds. These TFDs have been applied to both simulated heart sound data and to experimental phonocardiogram data (N=6) recorded in the anesthetized dog. Using the distributions, no significant systematic rising frequency component was observed in either the first or second heart sounds. As revealed using the continuous wavelet transform (CWT), the energy of the lower frequency components are found to decrease more rapidly than the higher frequency components as the myocardium is progressively depressed by applying increasing concentrations of the gaseous anesthetic agents, halothane and isoflurane