---
id: "2026-08-27-cartesia-sonic-3-6"
url: "https://postcutoff.com/e/2026-08-27-cartesia-sonic-3-6/"
as_of: "2026-11-13T13:49:00+01:00"
date: "2026-08-27"
date_precision: day
category: model-release
importance: 3
confidence: high
status: [Confirmed]
sources: 4
editor: human editor
human_review: null
version: "2026-10-04"
---

As of: 2026-11-13 13:49 CET.
Researched and written by AI agents (Claude Opus 5.5 in Claude Code), with a human editor. How we work: https://postcutoff.com/about/
Canonical page: https://postcutoff.com/e/2026-08-27-cartesia-sonic-3-6/

# 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 Artificial Analysis Speech Arena (~1279 Elo) until ElevenLabs' Eleven v4 took the top spot on 2026-09-28. Cartesia also shipped the Ink-2 streaming STT (2026-07-09) with built-in turn detection.

## Key facts
- API id sonic-3.6 (snapshot sonic-3.6-2026-08-27); backwards compatible with sonic-3.5
- <90 ms reply; ~132 chars/s generation (~2x Sonic 3 Conversational); 99.9% uptime SLA
- 44 languages with instant voice cloning; locale-aware numbers/dates
- Artificial Analysis: #1 at ~1279 Elo (25 Sept 2026), #2 (1275) behind Eleven v4 on 29 Sept
- sonic-2, sonic-turbo and sonic-3 snapshots sunset 2026-10-20

## What happened

Cartesia updated its Sonic TTS again: Sonic-3.5 in May, Sonic-3.6 in August. The update focused on naturalness, accent retention and faithful reading of structured content.

## Why it matters

Voice-agent TTS competition moved fast in Aug-Sept 2026. Cartesia, Inworld (TTS-2), Google (Gemini 3.8 Flash TTS), Alibaba and ElevenLabs (v4) swapped the Artificial Analysis #1 spot within weeks. Cartesia's SSM architecture is the main non-transformer contender at the frontier.

## Your AI and this story

- GPT-6 Astra (training cutoff April 2026): 119 days after its cutoff
- Claude Opus 5.5 (training cutoff June 2026): 58 days after its cutoff
- Gemini 4 Hydrogen (training cutoff March 2026): 149 days after its cutoff
- Grok 4.7 (training cutoff May 2026): 88 days after its cutoff

## Sources

1. [Cartesia: Introducing Sonic-3.6](https://www.cartesia.ai/blog/sonic-3.6) (cartesia.ai, official)
2. [Cartesia docs: Sonic 3.6](https://docs.cartesia.ai/build-with-cartesia/tts-models/latest) (docs.cartesia.ai, docs)
3. [Cartesia: Introducing Ink-2](https://www.cartesia.ai/blog/introducing-ink-2) (cartesia.ai, official)
4. [Artificial Analysis TTS leaderboard](https://artificialanalysis.ai/text-to-speech/leaderboard/provider-voice) (artificialanalysis.ai, official)

## Changes

- 2026-09-29 (filed): Created

## Related

- 2026-09-28: [ElevenLabs launches Eleven v4 and Eleven v4 Turbo, #1 on Artificial Analysis TTS arena](https://postcutoff.com/e/2026-09-28-elevenlabs-eleven-v4/index.md)
- 2026-09-15: [Google ships Gemini 3.8 Live voice models and Gemini 3.8 Flash TTS with voice design and cloning](https://postcutoff.com/e/2026-09-15-gemini-3-8-live-and-tts/index.md)
- 2026-08-31: [Inworld Realtime TTS-2 reaches GA with audio-aware, prompt-directed speech](https://postcutoff.com/e/2026-08-31-inworld-realtime-tts-2/index.md)
- Models: [Cartesia Sonic-3.6](https://postcutoff.com/m/cartesia-sonic-3-6/) (`cartesia-sonic-3-6`)