Inworld
inworld-tts-2 (reasoning)
Measured 2026-10-30
Build voice agents on Speko →inworld-tts-2 (reasoning) is measured here for comparison — it is not one of the models Speko routes.
Naturalness
—
Win % · 95% CI
—
Drift
11
Synth p50
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Robustness
0.82
Fined:
• fatal · ordinals (×0.5) — never said “one thousandth” (7 of 7 transcripts)
→ we sent “This is our 1,000th order.”
→ it said “This is our one, zeroth order.”
• minor · times · promptable — said “slash” out loud (6 of 7 transcripts)
→ we sent “Meet at 8:45 a.m. PT / 11:45 a.m. ET.”
→ it said “Meet at eight forty-five a.m. Pacific Time slash eleven forty-five a.m. Eastern Time”
• minor · dates · promptable (international, ×0.4) — said “slash” out loud (7 of 7 transcripts)
→ we sent “The lease ends 2025/06/30.”
→ it said “The lease ends two thousand twenty-five slash zero six slash thirty.”
Cost / 1M chars
$25.0
Same characters billed as reasoning off.
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