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

G Jamous·L G Durand·Y E Langlois·T Lanthier·P Pibarot·S Carioto
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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 16 ms spreads out low-frequency components into the higher frequencies and generates a spectrographic representation with poor frequency resolution (> or = 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.

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AnimalsDogsModels, CardiovascularPhonocardiographySignal Processing, Computer-AssistedTime FactorsJournal ArticleResearch Support, Non-U.S. Gov't

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G Jamous, L G Durand, Y E Langlois, T Lanthier, P Pibarot, S Carioto. 1992. Optimal time-window duration for computing time/frequency representations of normal phonocardiograms in dogs.. https://doi.org/10.1007/bf02457829

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