Rated for
13 text-to-speech (TTS) models, ordered speed first: by speed tier and P95 time to first audio on Coval, then the models Coval does not measure, by name. No combined score.
Data checked on October 22, 2026 · updated after each benchmark capture
13 text-to-speech (TTS) models are fast enough for a voice agent on Coval's 30-day measurement: they sit in the first two speed tiers, Headroom and Fast enough, on their P95 time to first audio. People leave about 200 ms between turns in conversation (Stivers et al., PNAS, 2009); a voice agent also has to transcribe and wait for a language model, so the text-to-speech stage is where the wait can be brought close to zero.
A voice agent is judged on every turn, not the average one. The P95 is the slowest one turn in twenty, the one a caller notices. The tiers break where the data has gaps, so no model sits on a boundary. Models Coval does not measure are not listed.
Alibaba Qwen3 TTS 1.7b is an open-weights text-to-speech (TTS) API from Alibaba (Qwen), served by Baseten, measured by one independent benchmark, Coval.
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.
Deepgram Flux TTS is a proprietary text-to-speech (TTS) API from Deepgram, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
ElevenLabs Eleven v4 Turbo is a proprietary text-to-speech (TTS) API from ElevenLabs, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
ElevenLabs Flash v2.5 is a proprietary text-to-speech (TTS) API from ElevenLabs, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
Fish Audio Drama 3 Preview is an open-weights text-to-speech (TTS) API from Fish Audio, measured by two independent benchmarks: Artificial Analysis and Coval.
Fluxions vui is a proprietary text-to-speech (TTS) API from Fluxions, measured by one independent benchmark, Coval.
Gradium TTS is a proprietary text-to-speech (TTS) API from Gradium, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.
Inworld Realtime TTS-2 is a proprietary text-to-speech (TTS) API from Inworld, measured by three independent benchmarks: Artificial Analysis, 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.
Palabra TTS v1 is a proprietary text-to-speech (TTS) API from Palabra, measured by two independent benchmarks: Coval and Speko.
SpeechifyAI Simba 3.0 is a proprietary text-to-speech (TTS) API from Speechify, measured by two independent benchmarks: Artificial Analysis and Coval.
SpeechifyAI Simba 3.2 is a proprietary text-to-speech (TTS) API from Speechify, measured by three independent benchmarks: Artificial Analysis, Coval and Speko.