What are Lightweight Text-to-Speech Models?
Lightweight text-to-speech (TTS) models are specialized AI systems designed to convert written text into natural-sounding speech with minimal computational requirements. Using advanced deep learning architectures, they deliver high-quality voice synthesis while maintaining efficiency and low latency. These models enable developers and creators to integrate voice capabilities into applications with unprecedented ease and performance. They foster innovation, democratize access to powerful speech synthesis tools, and enable a wide range of applications from virtual assistants and accessibility features to content creation and multilingual communication solutions.
FunAudioLLM/CosyVoice2-0.5B
CosyVoice 2 is a streaming speech synthesis model based on a large language model, employing a unified streaming/non-streaming framework design. The 0.5B parameter model achieves ultra-low latency of 150ms in streaming mode while maintaining synthesis quality almost identical to non-streaming mode. It supports Chinese (including dialects: Cantonese, Sichuan dialect, Shanghainese, Tianjin dialect), English, Japanese, Korean, and cross-lingual scenarios with fine-grained control over emotions and dialects.
FunAudioLLM/CosyVoice2-0.5B: Ultra-Low Latency Streaming Synthesis
CosyVoice 2 is a streaming speech synthesis model based on a large language model, employing a unified streaming/non-streaming framework design. The model enhances the utilization of the speech token codebook through finite scalar quantization (FSQ), simplifies the text-to-speech language model architecture, and develops a chunk-aware causal streaming matching model that supports different synthesis scenarios. In streaming mode, the model achieves ultra-low latency of 150ms while maintaining synthesis quality almost identical to that of non-streaming mode. Compared to version 1.0, the pronunciation error rate has been reduced by 30%-50%, the MOS score has improved from 5.4 to 5.53, and fine-grained control over emotions and dialects is supported. The model supports Chinese (including dialects: Cantonese, Sichuan dialect, Shanghainese, Tianjin dialect, etc.), English, Japanese, Korean, and supports cross-lingual and mixed-language scenarios. Pricing from SiliconFlow is $7.15/M UTF-8 bytes.
Pros
- Ultra-low latency of 150ms in streaming mode.
- Lightweight 0.5B parameter architecture.
- 30-50% reduction in pronunciation error rate vs v1.0.
Cons
- Smaller parameter count than some competing models.
- May require technical expertise for optimal configuration.
Why We Love It
- It delivers production-ready streaming speech synthesis with exceptional quality and ultra-low latency, making it perfect for real-time applications while maintaining lightweight efficiency.
fishaudio/fish-speech-1.5
Fish Speech V1.5 is a leading open-source text-to-speech model employing an innovative DualAR architecture with dual autoregressive transformer design. Trained on over 300,000 hours of data for English and Chinese, and over 100,000 hours for Japanese, it achieved an ELO score of 1339 in TTS Arena evaluations with outstanding accuracy: 3.5% WER and 1.2% CER for English, and 1.3% CER for Chinese.
fishaudio/fish-speech-1.5: Premium Multilingual Synthesis
Fish Speech V1.5 is a leading open-source text-to-speech (TTS) model. The model employs an innovative DualAR architecture, featuring a dual autoregressive transformer design. It supports multiple languages, with over 300,000 hours of training data for both English and Chinese, and over 100,000 hours for Japanese. In independent evaluations by TTS Arena, the model performed exceptionally well, with an ELO score of 1339. The model achieved a word error rate (WER) of 3.5% and a character error rate (CER) of 1.2% for English, and a CER of 1.3% for Chinese characters. This extensive training and innovative architecture make it ideal for high-quality multilingual speech synthesis applications. Pricing from SiliconFlow is $15/M UTF-8 bytes.
Pros
- Innovative DualAR dual autoregressive architecture.
- Massive training data: 300K+ hours for EN/CN.
- Top ELO score of 1339 in TTS Arena.
Cons
- Higher pricing at $15/M UTF-8 bytes on SiliconFlow.
- May require more computational resources than smaller models.
Why We Love It
- It combines cutting-edge architecture with massive training data to deliver top-tier speech quality and accuracy, making it the gold standard for multilingual text-to-speech applications.
IndexTeam/IndexTTS-2
IndexTTS2 is a breakthrough auto-regressive zero-shot text-to-speech model offering precise duration control—crucial for video dubbing applications. It features disentanglement between emotional expression and speaker identity, enabling independent control over timbre and emotion. With GPT latent representations and a three-stage training paradigm, it outperforms state-of-the-art models in word error rate, speaker similarity, and emotional fidelity.
IndexTeam/IndexTTS-2: Zero-Shot Voice Cloning with Emotion Control
IndexTTS2 is a breakthrough auto-regressive zero-shot Text-to-Speech (TTS) model designed to address the challenge of precise duration control in large-scale TTS systems, which is a significant limitation in applications like video dubbing. It introduces a novel, general method for speech duration control, supporting two modes: one that explicitly specifies the number of generated tokens for precise duration, and another that generates speech freely in an auto-regressive manner. Furthermore, IndexTTS2 achieves disentanglement between emotional expression and speaker identity, enabling independent control over timbre and emotion via separate prompts. To enhance speech clarity in highly emotional expressions, the model incorporates GPT latent representations and utilizes a novel three-stage training paradigm. To lower the barrier for emotional control, it also features a soft instruction mechanism based on text descriptions, developed by fine-tuning Qwen3, to effectively guide the generation of speech with the desired emotional tone. Experimental results show that IndexTTS2 outperforms state-of-the-art zero-shot TTS models in word error rate, speaker similarity, and emotional fidelity across multiple datasets. Pricing from SiliconFlow is $7.15/M UTF-8 bytes for both input and output.
Pros
- Breakthrough zero-shot voice cloning capability.
- Precise duration control for video dubbing.
- Independent control of timbre and emotion.
Cons
- More complex setup for advanced emotion control features.
- May require emotional prompt engineering for optimal results.
Why We Love It
- It revolutionizes zero-shot TTS with unprecedented control over duration, emotion, and speaker identity—perfect for professional content creation, dubbing, and applications requiring nuanced emotional expression.
TTS Model Comparison
In this table, we compare 2025's leading lightweight text-to-speech models, each with unique strengths. For ultra-low latency streaming, FunAudioLLM/CosyVoice2-0.5B delivers exceptional performance. For multilingual accuracy and quality, fishaudio/fish-speech-1.5 leads the pack. For zero-shot voice cloning with emotion control, IndexTeam/IndexTTS-2 sets the standard. This side-by-side view helps you choose the right tool for your specific voice synthesis needs.
| Number | Model | Developer | Subtype | Pricing (SiliconFlow) | Core Strength |
|---|---|---|---|---|---|
| 1 | FunAudioLLM/CosyVoice2-0.5B | FunAudioLLM | Text-to-Speech | $7.15/M UTF-8 bytes | 150ms ultra-low latency streaming |
| 2 | fishaudio/fish-speech-1.5 | fishaudio | Text-to-Speech | $15/M UTF-8 bytes | Top ELO score multilingual quality |
| 3 | IndexTeam/IndexTTS-2 | IndexTeam | Text-to-Speech | $7.15/M UTF-8 bytes | Zero-shot with emotion control |
Frequently Asked Questions
Our top three picks for 2025 are FunAudioLLM/CosyVoice2-0.5B, fishaudio/fish-speech-1.5, and IndexTeam/IndexTTS-2. Each of these models stood out for their innovation, performance, and unique approach to solving challenges in text-to-speech synthesis, streaming capabilities, multilingual support, and emotional voice control.
Our in-depth analysis shows several leaders for different needs. FunAudioLLM/CosyVoice2-0.5B is the top choice for real-time streaming applications requiring ultra-low latency. For creators who need the highest quality multilingual synthesis with exceptional accuracy, fishaudio/fish-speech-1.5 is the best option. For applications requiring zero-shot voice cloning with precise emotion and duration control, such as video dubbing, IndexTeam/IndexTTS-2 leads the way.