Official provider results
Sonic 3.6 launch evaluation
Cartesia’s August 27, 2026 launch post reports independent controlled-voice Elo ratings, blind preference win rates against Eleven v3, response latency, and locale coverage for Sonic 3.6.
Source snapshots refreshed
Five measurement lanesVOICE / S2S
Reasoning, task completion, conversation dynamics, experience, and latency stay separate.
Benchmark profile
- Scope
- independent controlled-voice Elo versus Sonic 3.5 and Eleven v3, blind head-to-head listener preference by locale, reply latency, and locale count
- Primary metric
- Elo rating and preference win rate (higher is better)
- Owner
- Cartesia
- Available evidence
- Exact figures published in the official launch post
What it measures
Voice experience
Is the exchange natural, robust, and responsive?
Latency
How long do responses, tool calls, and full tasks take?
Available results
- Independent controlled-voice Elo
- 1120
- US English preference vs Eleven v3
- 92%
- Reply latency
- Under 90 ms
- Locales
- 61
#1 at launch
Sonic 3.5 scored 1095 and ElevenLabs Eleven v3 1066.
Provider-run blind test
UK English 72%, Australian English 77%, French 86%, Spain Spanish 91%.
Provider-reported
Generates about 132 characters per second, nearly 2x v3 Conversational.
Documented
11 Indic locales; Odia and Urdu launch above 96% transcript accuracy.
Interpretation limit
Provider-reported results; the Elo figures are Cartesia’s citation of an independent speech leaderboard at launch and the preference tests are Cartesia-run.