ON TIMING IN TIME-FREQUENCY ANALYSIS OF SPEECH SIGNALS

The objective of this paper is to demonstrate the importance of positi on of the analysis time window in time-frequency analysis of speech si gnals. Speech signals contain information about the time varying chara cteristics of the excitation source and the vocal tract system. Resolu tion in both the temporal and spectral domains is essential for extrac ting the source and system characteristics from Speech signals. It is not only the resolution, as determined by the analysis window in the t ime domain, but also the position of the window with respect to the pr oduction characteristics that is important for accurate analysis of sp eech signals. In this context, we propose an event-based approach for speech signals. We define the occurrence of events at the instants cor responding to significant excitation of the vocal tract system. Knowle dge of these instants enable us to place the analysis window suitably for extracting the characteristics of the excitation source and the vo cal tract system even from short segments of data. We present a method of extracting the instants of significant excitation from speech sign als. We show that with the knowledge of these instants it is possible to perform prosodic manipulation of speech and also an accurate analys is of speech for extracting the source and system characteristics.