xAI Grok
grok-tts
Measured 2026-07-03
Naturalness
1495
Win % · 95% CI
48%
42–55%
Drift
15
Synth p50
272ms
272–325 p50–p90
Robustness
0.43
Fined:
• fatal · currency — dropped the minus sign (7 of 7 transcripts)
→ we sent “Your balance is -$1,204.50 as of today.”
→ it said “Your balance is $1,204.50 as of today.”
• minor · dates — said “slash” out loud; a prompt fixes this (3 of 7 transcripts)
→ we sent “Your slot is 03/09 this year.”
→ it said “Your slot is zero three slash zero nine this year.”
• minor · dates (international, ×0.4) — kept the value but never said “march”; a prompt fixes this (4 of 7 transcripts)
→ we sent “The order shipped on 2026-03-09.”
→ it said “The order shipped on twenty twenty six zero three zero nine.”
• fatal · decimals — dropped the minus sign (1 of 7 transcripts)
→ we sent “Growth slowed to -0.5% this month.”
→ it said “Growth slowed to 0.5% this month.”
Cost / 1M chars
$15.0
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