DETERMINATION OF INSTANTS OF SIGNIFICANT EXCITATION IN SPEECH USING GROUP DELAY FUNCTION

A new method for determining the instants of significant excitation in speech signals is proposed. Here, significant excitation refers prima rily to the instant of glottal closure within a pitch period in voiced speech, The method is based on the global phase characteristics of mi nimum phase signals, The average slope of the unwrapped phase of the s hort-time Fourier transform of linear prediction residual is calculate d as a function of time, Instants where the phase slope function makes a positive zero-crossing are identified as significant excitations, T he method is discussed in a source-filter context of speech production , The method is not sensitive to the characteristics of the filter, Th e influence of the type, length, and position of the analysis window i s discussed, The method works well for all types of voiced speech in m ale as well as female speech but, in all cases, under noise-free condi tions only.