Wideband Harmonic Model: Alignment and Noise Modeling for High Quality Speech Synthesis

Speech sinusoidal modeling has been successfully applied to a broad range of speech analysis, synthesis and modification tasks. However, developing a high fidelity full band sinusoidal model that preserves its high quality on speech transformation still remains an open research problem. Such a system can be extremely useful for high quality speech synthesis. In this paper we present an enhanced harmonic model representation for voiced/mixed wide band speech that is capable of high quality speech reconstruction and transformation in the parametric domain. Two key elements of the proposed model are a proper phase alignment and a decomposition of a speech frame to "deterministic" and dense "stochastic" harmonic model representations that can be separately manipulated. The coupling of stochastic harmonic representation with the deterministic one is performed by means of intra-frame periodic energy envelope, estimated at analysis time and preserved during original/transformed speech reconstruction. In addition, we present a compact representation of the stochastic harmonic component, so that the proposed model has less parameters than the regular full band harmonic model, with better Signal to Reconstruction Error performance. On top of that, the improved phase alignment of the proposed model provides better phase coherency in transformed speech, resulting in better quality of speech transformations. We demonstrate the subjective and objective performance of the new model on speech reconstruction and pitch modification tasks. Performance of the proposed model within unit selection TTS is also presented.