Emotional Dimension Control in Language Model-Based Text-to-Speech: Spanning a Broad Spectrum of Human Emotions

Abstract: Current emotional text-to-speech systems face challenges in conveying the full spectrum of human emotions, largely due to the inherent complexity of human emotions and the limited range of emotional labels in existing speech datasets. To address these limitations, this paper introduces a TTS framework that provides flexible user control over three emotional dimensions - pleasure, arousal, and dominance - enabling the synthesis of a diverse array of emotional styles. The framework leverages an emotional dimension predictor, trained soley on categorical labels from speech data and grounded in earlier psychological research, which is seamlessly integrated into a LLM-based TTS system. Experimental results demonstrates that the proposed framework effectively learns emotional styles from expressive speech, eliminating the need for explicit emotion labels during TTS training, while enhancing the naturalness and diversity of synthesized emotional speech.