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Abstract
Spectral analysis of sounds produced in vitro by mitral valve prostheses placed in a specially designed flow simulator has been carried out using a short-time Fourier representation of the recorded signal. Time variations of power spectra are displayed as a three-dimensional plot. Sounds produced by three types of valves, namely ball and cage, tilting disk and porcine values, were analysed. Each valve type produced a characteristic spectrogram: and, for a given valve, spectrograms were reproducible lo within a margin of 5 dB. The simulator may be used to detect structural deficiencies and functional abnormalities of prosthetic heart valves. In addition to quantifying the noise level of mechanical valves, the system may be used for quality control purposes to identify faulty valves.