ON THE ROBUSTNESS OF THE QUASI-HARMONIC MODEL OF SPEECH

In this paper we discuss the robustness of the Quasi-Harmonic model, QHM, previously suggested for speech analysis [1] and AM-FM decomposition of speech [2]. Assuming a frame by frame analysis, QHM suggests an iterative estimator for the actual fre-quencies of the speech components at the center of analysis window. In this paper, we show that this is a biased estimator and then, we compute analytically and numerically the bias of the estimator showing its dependence on the type and length of the analysis win-dow. Moreover, we analyze the robustness of the QHM estimator in white Gaussian noise, showing that the suggested iterative estimator asymptotically attains the corresponding Cramer-Rao lower bound even in adverse noisy conditions. Examples of synthetic signals are provided to support our analysis