Sub-100ms AI voice synthesis - the fastest TTS for real-time applications and automation pipelines
1M characters free; then $0.003 per 1K characters
What Is Cartesia Sonic-2?
Cartesia Sonic-2 is an AI audio generation model developed by Cartesia AI Inc. Cartesia's Sonic-2 achieves time-to-first-audio below 100ms - 3–5x faster than ElevenLabs Turbo. While ElevenLabs remains slightly ahead on absolute voice quality, Sonic-2 closes the gap significantly while dramatically outpacing on latency. This makes Cartesia the choice for real-time conversational AI agents, live-stream TTS, and high-throughput content production pipelines where speed is critical. Supports 17 languages with the Multilingual variant. Voice cloning from a 3-second sample.
Overview
| Description | Cartesia's Sonic-2 achieves time-to-first-audio below 100ms - 3–5x faster than ElevenLabs Turbo. While ElevenLabs remains slightly ahead on absolute voice quality, Sonic-2 closes the gap significantly while dramatically outpacing on latency. This makes Cartesia the choice for real-time conversational AI agents, live-stream TTS, and high-throughput content production pipelines where speed is critical. Supports 17 languages with the Multilingual variant. Voice cloning from a 3-second sample. |
| Developer | Cartesia AI Inc |
| Version | Sonic-2 / Sonic Multilingual |
| Category | Audio Model |
| Status | API / Dev |
| Pricing | 1M characters free; then $0.003 per 1K characters |
Capabilities7
| 1 | Sub-100ms time-to-first-audio latency |
| 2 | Voice cloning (3-second sample) |
| 3 | 17+ languages (Sonic Multilingual) |
| 4 | Emotion/speed/pitch controls |
| 5 | WebSocket real-time streaming |
| 6 | Batch API for high-volume production |
| 7 | Custom voice fine-tuning |
Model Tiers
| Tier | Speed | Quality | Pricing |
|---|---|---|---|
| Free | <100ms | 1M chars/mo free | Free |
| Scale | <100ms | Pay-as-you-go | $0.003/1K chars ($3/1M) |
Output Specs
| Languages | 17 languages supported |
Prompting Tips
Prompt
POST /v1/audio/speech { model: 'sonic-2', voice_id: 'your-cloned-voice', input: 'Dynamic response text here', speed: 1.1, emotion: 'positivity:high' }
Expected Result
Sub-100ms first-audio response for live AI agent
Prompt
Loop CSV of 1000 video scripts → POST each to Cartesia API → receive MP3/PCM → merge with video frames via FFmpeg → output 1000 videos
Expected Result
1000 voiced videos generated in parallel without quality loss
Best Fit
Best For
- ✓Real-time AI voice agents
- ✓High-volume automation pipelines
- ✓Live-stream TTS overlays
- ✓Low-latency conversational AI
Watch Out For
- ✗Simple occasional voiceovers - ElevenLabs' web app is easier
- ✗50+ language coverage - ElevenLabs supports 32 vs Cartesia's 17
Access Via
Frequently Asked Questions
What is Cartesia Sonic-2?
Cartesia Sonic-2 is a audio AI model developed by Cartesia AI Inc. Sub-100ms AI voice synthesis - the fastest TTS for real-time applications and automation pipelines. Cartesia's Sonic-2 achieves time-to-first-audio below 100ms - 3–5x faster than ElevenLabs Turbo. While ElevenLabs remains slightly ahead on absolute voice quality, Sonic-2 closes the gap significantly while dramatically outpacing on latency. This makes Cartesia the choice for real-time conversationa...
How much does Cartesia Sonic-2 cost?
1M characters free; then $0.003 per 1K characters. Free: Free; Scale: $0.003/1K chars ($3/1M)
What can Cartesia Sonic-2 create?
Cartesia Sonic-2 is best for: Real-time AI voice agents, High-volume automation pipelines, Live-stream TTS overlays, Low-latency conversational AI. Key capabilities include Sub-100ms time-to-first-audio latency, Voice cloning (3-second sample), 17+ languages (Sonic Multilingual), Emotion/speed/pitch controls.
How do you access Cartesia Sonic-2?
Cartesia Sonic-2 is available through: Cartesia API (api), Cartesia Python SDK (api).
Is Cartesia Sonic-2 free to use?
Yes, Cartesia Sonic-2 offers free access. Free.