Nonlinear estimation of missing ΔLSF parameters by a mixture of Dirichlet distributions

In packet networks, a reliable scheme to handle packet loss during speech transmission is of great importance. As a common representation of the linear predictive coding (LPC) model, the line spectral frequency (LSF) parameters are widely used in speech quantization and transmission. In this paper, we propose a novel scheme to estimate the missing values occurring during LPC model transmission. In order to exploit the boundary and ordering properties of the LSF parameters, we utilize the ΔLSF representation and apply the Dirichlet mixture model (DMM) to capture the correlations among the elements in the ΔLSF vector. With the conditional distribution of the missing part given the received part, an optimal nonlinear minimum mean square error estimator for the missing values is proposed. Compared to the previously presented Gaussian mixture model based method, the proposed DMM based nonlinear estimator shows a convincing improvement.