Abstract
The closing sounds of St. Jude bileaflet heart valve sounds recorded in air are studied, and the relation between the frequency spectrum of these signals and PCG (phonocardiography) signals recorded from the patients who have the same prosthesis implanted in aortic position is discussed. During the experiment one of the leaflets is fixed and loaded by different methods to observe the possible variation in the signals. It is observed that the frequency spectra of the signals recorded in air have a power spectrum similar to the transfer function of the amplifier in the frequency range 100-1500 Hz. PCG signals have all the frequency components between 100 and 500 Hz.< >