Supertone releases Supertonic 3: 99M-parameter on-device TTS model supporting 31 languages

Supertone has released Supertonic 3, a 99M-parameter text-to-speech model that runs entirely on-device using ONNX Runtime. The model expands language support from 5 to 31 languages compared to Supertonic 2 and requires no GPU for inference.

Technical Specifications

• Parameters: 99 million across ONNX assets
• Languages: 31 (expanded from 5 in Supertonic 2)
• Inference: CPU-only via ONNX Runtime, no cloud calls required
• Model type: Text-to-speech
• License: OpenRAIL-M for model weights, MIT for sample code

Performance Claims

According to Supertone, Supertonic 3 achieves competitive word error rates (WER) and character error rates (CER) against larger open-source TTS models like VoxCPM2, which range from 0.7B to 2B parameters. The company provides benchmark comparisons showing the model runs faster on CPU than larger baselines measured on A100 GPU.

Supertonic 3 claims improvements over version 2 in three areas: reduced repeat and skip failures during reading, higher speaker similarity across shared languages, and the 6x expansion in language coverage.

New Features

• Expression tags: Supports <laugh>, <breath>, and <sigh> tags for expressive synthesis
• Improved stability: Fewer reading errors on both short and long text inputs
• 31 languages: English, Korean, Japanese, Arabic, Bulgarian, Czech, Danish, German, Greek, Spanish, Estonian, Finnish, French, Hindi, Croatian, Hungarian, Indonesian, Italian, Lithuanian, Latvian, Dutch, Polish, Portuguese, Romanian, Russian, Slovak, Slovenian, Swedish, Turkish, Ukrainian, Vietnamese

Deployment

The model ships as ONNX assets and runs through a Python SDK. Users can install via pip install supertonic and generate speech locally. The SDK auto-downloads model assets from Hugging Face on first run.

from supertonic import TTS
tts = TTS(auto_download=True)
style = tts.get_voice_style(voice_name="M1")
wav, duration = tts.synthesize(text, voice_style=style, lang="en")

What This Means

Supertonic 3 targets the growing demand for privacy-preserving, on-device AI inference. At 99M parameters, the model is 7-20x smaller than comparable open TTS systems, making it practical for browser and edge deployment where GPU access is limited or unavailable. The CPU-only requirement and sub-100MB footprint address real constraints in mobile and embedded applications.

The 31-language support positions Supertonic 3 as a lightweight alternative to larger multilingual TTS systems. However, without independent benchmarks, it remains unclear how the model's accuracy-size tradeoff compares to cloud-based alternatives or other on-device TTS solutions across different hardware profiles and use cases.