Application of smoothed Wigner distribution (WD) to speech signals
Harinath Garudadri, André-Pierre Benguerel, JOHN H.V. GILBERT, M.P. Beddoes · The Journal of the Acoustical Society of America · 1986
The WD is a powerful tool for the simultaneous time-frequency analysis of time-varying signals [Martin and Flandrin, IEEE Trans. Acoust. Speech Signal Process. ASSP-33 (Dec. 1985)]. For signals with simple time-frequency structures (e.g., frequency-modulated signals), the WD provides excellent resolution in the time-frequency (t − ω) plane, as compared with conventional short-time spectral analysis techniques. The interpretation of the WD becomes more difficult as the time-frequency relationship of the signal gets more complex (e.g., in speech), because of the presence of cross terms and of regions below (i.e., negative) the t − ω plane. This disadvantage can be overcome by smoothing the WD in the t and ω directions over a region TΩ > 1 (T and Ω are the “smear” values in time and frequency) [Janssen and Claasen, IEEE Trans. Acoust. Speech Signal Process. ASSP-33 (Aug. 1985)]. Such a smoothing process, however, makes the WD and the spectrogram equivalent in terms of the time and frequency resolutions. This presentation is directed towards comparing the performances of the WD (with partial smoothing, i.e., T < 1) and the spectrogram. Nonspeech signals as well as speech signals will be used to demonstrate the application of WD to the analysis of speech signals. [Work supported by NSERC, Canada.]