Statistical Parametric Speech Synthesis Using Deep Gaussian Processes

This paper proposes a framework of speech synthesis based on deep Gaussian processes (DGPs), which is a deep architecture model composed of stacked Bayesian kernel regressions. In this method, we train a statistical model of transformation from contextual features to speech parameters in a similar manner to deep neural network (DNN)-based speech synthesis. To apply DGPs to a statistical parametric speech synthesis framework, our framework uses an approximation method, doubly stochastic variational inference, which is suitable for an arbitrary amount of data. Since the training of DGPs is based on the marginal likelihood that takes into account not only data fitting, but also model complexity, DGPs are less vulnerable to overfitting compared with DNNs. In experimental evaluations, we investigated a performance comparison of the proposed DGP-based framework with a feedforward DNN-based one. Subjective and objective evaluation results showed that our DGP framework yielded a higher mean opinion score and lower acoustic feature distortions than the conventional framework.