41 ms median and 83 ms P95 time to first audio on Coval (30 days to October 22, 2026): Headroom speed tier.
Benchmark summary: Headroom speed tier on Coval's P95 (headroom to spend elsewhere in the turn).
Fluxions vui is a proprietary text-to-speech (TTS) API from Fluxions, measured by one independent benchmark, Coval.
Speed tier
HeadroomP95 at or under 101 ms. Headroom to spend elsewhere in the turn.
Data read October 22, 2026. No combined score: methodology
Gradium TTS vs Fluxions vui Fastest TTS APIs, by speed tierOn Coval's 30-day window ending October 22, 2026 (3,062 runs from US East), Fluxions vui starts speaking after 41.4 ms on a typical turn (median) and 83.2 ms on a slow turn (P95, the slowest one in twenty). That P95 is the lowest of the 32 models Coval measures, which puts it in the Headroom tier: headroom to spend elsewhere in the turn.
Neither Speko nor Artificial Analysis rates its voice quality.
Speko has not scored its pronunciation of numbers and dates.
Coval lists $9 per 1M characters (since Sep 24, 2026). List prices, as each source prints them.
Alibaba Qwen3 TTS Fast is an open-weights text-to-speech (TTS) API from Alibaba (Qwen), served by Nari Labs, measured by two independent benchmarks: Coval and Speko.
Inworld Realtime TTS-2 Flash is a proprietary text-to-speech (TTS) API from Inworld, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
Gradium TTS is a proprietary text-to-speech (TTS) API from Gradium, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.