Cartesia Sonic-3.6
Beta 2026-08-17, GA snapshot 2026-08-27. Header `Cartesia-Version: 2026-08-14`. Fully backwards compatible with Sonic-3.5 (snapshot 2026-05-04, which led AA's Controlled Voice Arena at its 2026-07-08 launch with 1,122 Elo). Scored 0.840 (#5) on Hume's Real-World VoiceEQ leaderboard (2026-09-24). sonic-3 snapshots (2025-10-27, 2026-01-12), sonic-2 and sonic-turbo sunset 2026-10-20. `sonic-preview` = beta channel; `sonic-latest` alias deprecated. Exact per-character USD price is plan-dependent (credits); figure above is derived. Also on AWS SageMaker JumpStart (Sonic 3, Feb 2026).
- Input
- text
- Output
- audio
- License
- proprietary
- Pricing
- per 1k characters: $0.037 (approx., derived: ~1 credit per character; Scale plan $299/mo for 8M credits (Startup $49 for 1.25M ≈ $0.039/1K). Artificial Analysis lists $49 per 1M chars) source
- Verified
- 2026-09-29
How to call it
| Provider | Model id | Endpoint / URL | Docs |
|---|---|---|---|
| Cartesia API | sonic-3.6 | https://api.cartesia.ai/tts/bytes (also /tts/sse and WebSocket) | docs |
| Cartesia API (pinned snapshot) | sonic-3.6-2026-08-27 | https://api.cartesia.ai/tts/bytes | — |
| Web app | — | play.cartesia.ai | — |
Notable capabilities (4)
- State-space-model TTS, sub-90 ms: Built on state space models (SSMs); replies in under 90 ms and generates ~132 chars/s (nearly 2x Sonic 3 Conversational). Listeners preferred it over Sonic-3.5 in up to 93% of blind tests across 15 locales. source
- 44 languages with instant cloning: Adds Odia and Urdu to Sonic-3.5's 42 languages; instant voice cloning; locale-aware reading of dates/numbers; confirmation codes and heteronyms without preprocessing. source
- Multilingual Voices (one voice, 25 languages) (found after launch): Launched 2026-09-23 on Sonic-3.6: 50+ library voices each speak up to 25 languages natively, and custom clones from ~10 s of audio carry their identity across languages via a `locale` parameter; native speakers rate each variant for accent and localization of dates, numbers and currency. source
- Top-2 on Artificial Analysis Speech Arena (found after launch): Ranked #1 (Elo ~1279) on the Artificial Analysis TTS leaderboard in mid/late Sept 2026, then #2 (Elo 1275) behind Eleven v4 after 2026-09-28. source
Cartesia's flagship low-latency TTS for voice agents.
curl -X POST https://api.cartesia.ai/tts/bytes -H "Authorization: Bearer $CARTESIA_API_KEY" -H "Cartesia-Version: 2026-08-14" \
-H "Content-Type: application/json" -d '{"model_id":"sonic-3.6","transcript":"Your code is 4 8 1 5.","voice":{"mode":"id","id":"<voice_id>"},"output_format":{"container":"wav","encoding":"pcm_s16le","sample_rate":44100}}' -o out.wav
Sources: https://docs.cartesia.ai/build-with-cartesia/tts-models/latest , https://docs.cartesia.ai/build-with-cartesia/tts-models/older-models , https://www.cartesia.ai/blog/sonic-3.6
Timeline entry
- Cartesia Sonic-3.6 goes GA and tops the Artificial Analysis Speech Arena ★★★
Cartesia made Sonic-3.6 generally available on 2026-08-27 (beta 2026-08-17), three months after Sonic-3.5. The state-space-model TTS replies in under 90 ms, supports 44 languages (adding Odia and Urdu) and was preferred over Sonic-3.5 in up to 93% of blind tests. In September it ranked #1 on the…