DeepConversion: Voice conversion with limited parallel training data

A deep neural network approach to voice conversion usually depends on a large amount of parallel training data from source and target speakers. In this paper, we propose a novel conversion pipeline, DeepConversion, that leverages a large amount of non-parallel, multi-speaker data, but requires only a small amount of parallel training data. It is believed that we can represent the shared characteristics of speakers by training a speaker independent general model on a large amount of publicly available, non-parallel, multi-speaker speech data. Such general model can then be used to learn the mapping between source and target speaker more effectively from a limited amount of parallel training data. We also propose a strategy to make full use of the parallel data in all models along the pipeline. In particular, the parallel data is used to adapt the general model towards the source-target speaker pair to achieve a coarse grained conversion, and to develop a compact Error Reduction Network (ERN) for a fine-grained conversion. The parallel data is also used to adapt the WaveNet vocoder towards the source-target pair. The experiments show that DeepConversion that only uses a limited amount of parallel training data, consistently outperforms the traditional approaches that use a large amount of parallel training data, in both objective and subjective evaluations. (C) 2020 The Authors. Published by Elsevier B.V.