Title: TTS-Hub: Leveraging Modular LoRAs and  Arithmetic Composition for Controllable Text-to-Speech
Primary area: generative models
Keywords: Controllable text-to-speech (TTS), modular Low-Rank Adaptation (LoRA), LoRA Composition

Abstract: Controllable text-to-speech (TTS) aims to generate speech from text while allowing control over prosodic and speaker-related attributes such as pitch, age, and accent. Existing controllable TTS methods primarily rely on natural language prompts to guide the synthesis process or utilize reference audio cloning to achieve control. However, prompt-based approaches often struggle with the cross-modal semantic gap between textual descriptions and intended speech attributes, leading to imprecise and coarse-grained control. Conversely, cloning methods depend heavily on reference audio samples and struggle to generalize beyond the characteristics seen in those samples, resulting in limited flexibility. To overcome these challenges, this paper proposes TTS-Hub, a novel controllable TTS framework that employs modular Low-Rank Adaptation (LoRA) components and their arithmetic-based composition to achieve fine-grained and flexible controllable TTS. Specifically, we construct a comprehensive Data Hub, which covers 6 high-level attribute categories and 32 fine-grained speech attributes. Leveraging this attribute-specific data, we fine-tune two mainstream TTS frameworks to obtain a corresponding LoRA Hub, where each modular LoRA is specialized for a specific speech attribute. At inference time, TTS-Hub selects the required LoRA modules and combines them through simple arithmetic composition to produce a fused LoRA that simultaneously encodes multiple attribute representations, enabling flexible and extensible multi-attribute control without retraining the backbone. Extensive experiments show that individual LoRAs provide precise single‑attribute control, while arithmetic composition yields flexible and interpretable multi‑attribute speech and consistently outperforms prompt‑based baselines. Code and data are available in supplementary materials.