SelfTTS: cross-speaker style transfer through explicit embedding disentanglement and self-refinement using self-augmentation
Authors: Lucas H. Ueda, João G. T. Lima, Pedro R. Corrêa, Flávio O. Simões, Mário U. Neto, Paula D. P. Costa · Universidade Estadual de Campinas (UNICAMP) and CPQD
This paper presents SelfTTS, a text-to-speech (TTS) model designed for cross-speaker style transfer that eliminates the need for external pre-trained speaker or emotion encoders. The architecture achieves emotional expressivity in neutral speakers through an explicit disentanglement strategy utilizing Gradient Reversal Layers (GRL) combined with cosine similarity loss to decouple speaker and emotion information. We introduce Multi Positive Contrastive Learning (MPCL) to induce clustered representations of speaker and emotion embeddings based on their respective labels. Furthermore, SelfTTS employs a self-refinement strategy via Self-Augmentation, exploiting the model’s voice conversion capabilities to enhance the naturalness of synthesized speech. Experimental results demonstrate that SelfTTS achieves superior emotional naturalness (eMOS) and robust stability in target timbre and emotion compared to state-of-the-art baselines.
Training speakers — ESD dataset
The two ESD speakers below were used during training exclusively with their neutral utterances (~350 samples each).
All emotional samples from both speakers were held out entirely and used only for evaluation in the cross-speaker emotional style transfer setup — the model must generalise to emotions it has never seen the target speaker express.
The cross-corpus speakers (LJ Speech, p226, and p231 from VCTK) were trained with a similar data budget to the neutral-only ESD speakers — approximately 350 utterances each — in order to maintain a fixed and comparable experimental setup across all conditions.
The Proposed (VC) variant utilizes the voice conversion branch of the model to perform style transfer.
Note on naturalness and intelligibility: Outputs from cross-corpus speakers may exhibit reduced naturalness and intelligibility due to the small amount of training data and the acoustic mismatch between the source corpus and ESD during style transfer. Scaling the data would likely mitigate these effects. However, we deliberately keep the data budget fixed to isolate the contributions of the proposed approach and to more clearly expose both its benefits and its current limitations.