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Cartesia

sonic-3.5

Measured 2026-07-03

Run sonic-3.5 on Speko →

One API, every model on this board.

Naturalness

1574

Win % · 95% CI

65%

58–71%

Drift

13

Synth p50

121ms

121–236 p50–p90

Robustness

0.18

Fined:

• fatal · currency — dropped the minus sign (7 of 7 transcripts)

→ we sent “The balance is -$12.50.”

→ it said “The balance is $12.50.”

• fatal · dates — never said “friday” or “sunday” (41 of 49 transcripts)

→ we sent “The fair runs Fri–Sun, Oct 9–11.”

→ it said “The fair runs Fryson, October ninth, eleven.”

• fatal · large numbers — never said “three point four million” (21 of 49 transcripts)

→ we sent “The clip hit 3.4M views and 1.2k shares.”

→ it said “The clip hit three point four M views and one point two K shares.”

+ 22 more fined

Cost / 1M chars

$50.0

1 credit/char on Pro, the cheapest paid plan; $39.2 at Startup, $37.4 at Scale. Cloned voices bill 1.5x.

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