Leveraging Low-Rank Adaptation for Parameter-Efficient Fine-Tuning in Multi-Speaker Adaptive Text-to-Speech Synthesis

Text-to-speech (TTS) technology is commonly used to generate personalized voices for new speakers. Despite considerable progress in TTS technology, personal voice synthesis remains problematic in achieving high-quality custom voices. In addressing this issue, fine-tuning a TTS model is a popular approach. However, it must be applied once for every new speaker, which results in both time-consuming model training and excessive storage of the TTS model parameters. Therefore, to support a large number of new speakers, a parameter-efficient fine-tuning (PEFT) approach must be used instead of full fine-tuning, as well as an approach to accommodate multiple speakers with a small number of parameters. To this end, this work first incorporates a low-rank adaptation-based fine-tuning method for variational inference with adversarial learning for end-to-end TTS (VITS) model. Next, the approach is extended with conditional layer normalization for multi-speaker fine-tuning, and the residual adapter is further applied to the text encoder outputs of the VITS model to improve the intelligibility and naturalness of the speech quality of personalized speech. The performance of the fine-tuned TTS models with different combinations of fine-tuning modules is evaluated using the Libri-TTS-100, VCTK, and Common Voice datasets, as well as a Korean multi-speaker dataset. Objective and subjective quality comparisons reveal that the proposed approach achieves speech quality comparable to that of a fully fine-tuned model, with around a 90% reduction in the number of model parameters.