ElevenLabs Eleven v4 Turbo
ElevenLabs Eleven v4 Turbo is a proprietary text-to-speech (TTS) API from ElevenLabs, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
200 ms median and 263 ms P95 time to first audio on Coval (30 days to October 22, 2026): Fast enough speed tier.
Benchmark summary: Fast enough speed tier on Coval's P95 (fast enough for most agents).
Deepgram Flux TTS is a proprietary text-to-speech (TTS) API from Deepgram, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
Speed tier
Fast enoughP95 from 138 ms to 263 ms. Fast enough for most agents.
Data read October 22, 2026. No combined score: methodology
Gradium TTS vs Deepgram Flux TTS Fastest TTS APIs, by speed tierOn Coval's 30-day window ending October 22, 2026 (3,199 runs from US East), Deepgram Flux TTS starts speaking after 199.8 ms on a typical turn (median) and 262.9 ms on a slow turn (P95, the slowest one in twenty). That P95 is 13th lowest of the 32 models Coval measures, which puts it in the Fast enough tier: fast enough for most agents. On the median it is a tie (gap under 10 ms) with ElevenLabs Eleven v4 Turbo. Speko's board plots it at 118 ms time to first audio from US East; its model page reports a 106 ms sweep.
Speko rates its naturalness at 1,550 Elo from blind A/B votes on phone-agent lines (17th highest of the 43 models Speko rates). In the Artificial Analysis Speech Arena it holds 1,052 ±13 Elo (95% interval), 65th highest of the 98 models Artificial Analysis rates; scores whose intervals overlap are a tie. In its Customer Service category, Artificial Analysis places it 35th, at 1,143 Elo.
Speko's pronunciation test on numbers, dates and currency scores it 0.2 on a 0-to-1 scale (25th highest of the 30 models Speko scores). This is the accuracy measure used here; Coval's word error rate separates models too little to compare them.
Artificial Analysis lists $45. Speko lists about $45. List prices, as each source prints them.
ElevenLabs Eleven v4 Turbo is a proprietary text-to-speech (TTS) API from ElevenLabs, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
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