Robustness of group-delay-based method for extraction of significant instants of excitation from speech signals

In this paper, we study the robustness of a group-delay-based method for de termining the instants of significant excitation in speech signals. These i nstants correspond to the instants of glottal closure for voiced speech, Th e method uses the properties of the global phase characteristics of minimum phase signals. Robustness of the method against noise and distortion is du e to the fact that the average phase characteristics of a signal is determi ned mainly by the strength of the excitation impulse. The strength of excit ation is determined by the energy of the residual error signal around the i nstant of excitation. We propose a-measure for the strength of the excitati on based on Frobenius norm of the differenced signal. The robustness of the group-delay-based method is illustrated for speech under different types o f degradations and for speech from different speakers.