CartesiaFish AudioAudio matchupSpeech output
Sonic 3.6vs.Fish Audio S2.1 Pro
Which model is better?
Sonic 3.6 does better in independent tests.
Pick Sonic 3.6 for
Pick Fish Audio S2.1 Pro for
Shared tests
Independent evaluators and leaderboards only, the newest shared snapshot per evaluator. With 95 % ranges a lead counts when they do not overlap; for hit rates, when it holds in a 95 % test. Without any uncertainty figure at most “slightly ahead”.
Artificial Analysis
Sonic 3.6 aheadSonic 3.6 is clearly ahead in 2 of 2 subtests, Fish Audio S2.1 Pro in none.
Artificial Analysis Controlled Voice Arena Elo
95 % ranges 1,135 to 1,159 and 996 to 1,022, as of November 3, 2026
Artificial Analysis Provider Voice Arena preference
95 % ranges 1,280 to 1,306 and 1,170 to 1,196, as of November 3, 2026
Source · latest November 3, 2026
DesignArena
Sonic 3.6 slightly aheadDesignArena Audio Realism Elo
as of October 28, 2026
Source · latest October 28, 2026
VoiceArena
Sonic 3.6 aheadVoiceArena TTS Elo: US English
95 % ranges 1,047 to 1,071 and 975 to 1,003, as of October 28, 2026
Source · latest October 28, 2026
All data side by side
Prices are verbatim from the provider, because audio models bill per minute, character or token.
| Sonic 3.6 | Fish Audio S2.1 Pro | |
|---|---|---|
| Task | Speech output | Speech output |
| Developer | Cartesia | Fish Audio |
| Status | Active | Active |
| Released | n/a | June 23, 2026 |
| Weights | proprietary | proprietary |
| Runs locally | no | no |
| Price | n/a | Free through 2026-11-30 under fair-use rules; changes with advance notice |
| Popularity (out of 100) | 39 | 0 |