Optimal time-window duration for computing time / frequency representations of normal phonocardiograms in dogs

Authors: Jamous, Ghaleb; Durand, Louis-Gilles; Langlois, Yves; Lanthier, Thérèse; Pibarot, Philippe; Carioto, Suzanne
Abstract: The optimal duration of the time-window used to compute the time-frequency representation (spectrogram) of the phonocardiogram was studied in four dogs by using intracardiac and thoracic measurements of the PCG. The power and cross-spectrograms of the intracardiac and thoracic PCGs were computed using a fast Fourier transform algorithm and a sine-cosine window with 10 per cent decaying functions. A coherence spectrogram was also computed for each dog to study the linear relationship between the two signals and determine the optimal time-window duration. Results show that the optimal range of the time-window duration is between 16 and 32 ms. A time-window shorter than 16ms spreads out low-frequency components into the higher frequencies and generates a spectrographic representation with poor frequency resolution (=62·5 Hz). A window larger than 32 ms increases the frequency resolution but smears the spectrographic representation of the signal in the time domain and thus cannot correctly reflect the time-varying properties of the signal. In both cases, the amplitude of the coherence function computed between the left ventricular and the thoracic phonocardiograms is overestimated.
Document Type: Article de recherche
Issue Date: 1 September 1992
Open Access Date: Restricted access
Document version: VoR
Permalink: http://hdl.handle.net/20.500.11794/8528
This document was published in: Medical and Biological Engineering and Computing, Vol. 30 (5), 503–508 (1992)
Alternative version: 10.1007/BF02457829
Collection:Articles publiés dans des revues avec comité de lecture

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