Voice AI BenchmarksBy

FLUXIONSTEXT-TO-SPEECH6,974 SAMPLES / 30 DAYSLAST RUN OCT 14, 2026, 15:30 UTC

official resource

vui text-to-speech benchmarks

vui, hosted by Fluxions, measures mean 59 ms time to first audio (1st of 32) and 2.1% word error rate (27th of 32) among TTS systems. Results cover the last 30 days. Coval benchmarks hosted endpoints daily using a consistent evaluation methodology. Last measured .

Vui is Fluxions' real-time text-to-speech model.

Time to First Audio#1 / 32
59ms
TTFA Network Roundtrip#1 / 32
46ms
TTFA Leading Silence#7 / 32
13ms
Word Error Rate#27 / 32
2.1%

Overview

Vui supports voice cloning and emotion controls, and Fluxions both creates and hosts the measured endpoint.

vui is tested every day on a fixed set of text prompts, measuring how quickly audible speech starts and how intelligible the result is.

Technical specifications

Made by
Fluxions
Hosted by
Fluxions
Source
Official API
Licensing
Proprietary
Deployment
Cloud
Region
US
Features
Emotion control, Voice cloning

How vui ranks

Full TTS dashboard
Time to First Audio — every measured TTS modelMilliseconds · lower is better · 30-day averageEvery TTS model ranked on Time to First Audio, with vui highlighted.
  1. #1vui59 ms
  2. #2Default63 ms
  3. #3Qwen3 TTS Fast68 ms
  4. #4TTS Flash 291 ms
  5. #5Qwen3 TTS 1.7b107 ms
  6. #6Simba 3.0111 ms
  7. #7Palabra TTS120 ms
  8. #8Simba 3.2126 ms
  9. #9drama3-preview167 ms
  10. #10TTS 2191 ms
  11. #11Flash v2.5192 ms
  12. #12Eleven v4 Turbo201 ms
Show all 32 models
  1. #13Flux TTS205 ms
  2. #14TTS RT v1255 ms
  3. #15TTS Rt v2256 ms
  4. #16Mist v3287 ms
  5. #17Phantom Z 3.4 conversational291 ms
  6. #18Sonic 3.5293 ms
  7. #19Aura 2297 ms
  8. #20Sonic 3.6299 ms
  9. #21Falcon 2300 ms
  10. #22Coda332 ms
  11. #23S2.1 Pro341 ms
  12. #24Grok TTS363 ms
  13. #25S1389 ms
  14. #26Lightning v3.1 Pro392 ms
  15. #27Daytona TTS486 ms
  16. #28Aura 2 En569 ms
  17. #29Chirp 3 HD597 ms
  18. #30Qwen3 TTS Flash Realtime718 ms
  19. #31S2.1 Pro Free850 ms
  20. #32GPT-4o mini TTS2585 ms
median of all models · 289 ms
TTS models over the last 30 days, ranked on Time to First Audio.
#ModelHostTTFAWERSamples
1vuiFluxions59 ms1,744
2Gradium TTS Beta 202609Gradium63 ms1,916
3Qwen3 TTS FastNari Labs68 ms1,916
4TTS Flash 2Inworld AI91 ms1,720
5Qwen3 TTS 1.7bBaseten107 ms1,248
6Simba 3.0SpeechifyAI111 ms1,915
7Palabra TTS v1Palabra120 ms1,576
8Simba 3.2SpeechifyAI126 ms1,912
9Drama 3 Preview Us EastFish Audio167 ms162
10TTS 2Inworld AI191 ms1,720
11Flash v2.5ElevenLabs192 ms1,906
12Eleven v4 TurboElevenLabs201 ms1,226
13Flux TTSDeepgram205 ms1,779
14TTS RT v1Soniox255 ms1,618
15TTS Rt v2Soniox256 ms1,615
16Mist v3Rime287 ms602
17Phantom Z 3.4 conversationalDeepdub291 ms1,651
18Sonic 3.5Cartesia293 ms1,916
19Aura 2Deepgram297 ms1,848
20Sonic 3.6Cartesia299 ms1,916
21Falcon 2Murf300 ms1,915
22CodaRime332 ms602
23S2.1 ProFish Audio341 ms1,916
24Grok TTSSpaceXAI363 ms1,911
25S1Fish Audio389 ms1,915
26Lightning v3.1 ProSmallest392 ms1,916
27Daytona TTSGuava486 ms1,152
28Aura 2 EnCloudflare569 ms1,915
29Chirp 3 HDGoogle597 ms1,916
30Qwen3 TTS Flash RealtimeAlibaba718 ms1,915
31S2.1 Pro FreeFish Audio850 ms1,909
32GPT-4o mini TTSOpenAI2585 ms1,846
Under-sampled models are excluded; tied models share a place. Dotted WER values split into substitutions, deletions and insertions on hover or tap.

Latency vs accuracy

TTFA vs WEREach point is one measured model · vui highlighted · 30-day averagesTime to First Audio against Word Error Rate for every measured TTS model, with vui highlighted.
Default — 63 ms, 1.9%Qwen3 TTS Fast — 68 ms, 1.8%TTS Flash 2 — 91 ms, 1.7%Qwen3 TTS 1.7b — 107 ms, 1.8%Simba 3.0 — 111 ms, 1.5%Palabra TTS — 120 ms, 2.6%Simba 3.2 — 126 ms, 1.9%drama3-preview — 167 ms, 2.0%TTS 2 — 191 ms, 1.6%Flash v2.5 — 192 ms, 1.8%Eleven v4 Turbo — 201 ms, 1.7%Flux TTS — 205 ms, 1.7%TTS RT v1 — 255 ms, 2.4%TTS Rt v2 — 256 ms, 2.4%Mist v3 — 287 ms, 2.1%Phantom Z 3.4 conversational — 291 ms, 1.8%Sonic 3.5 — 293 ms, 1.5%Aura 2 — 297 ms, 1.8%Sonic 3.6 — 299 ms, 1.5%Falcon 2 — 300 ms, 1.7%Coda — 332 ms, 9.5%S2.1 Pro — 341 ms, 1.5%Grok TTS — 363 ms, 1.6%S1 — 389 ms, 1.8%Lightning v3.1 Pro — 392 ms, 1.5%Daytona TTS — 486 ms, 1.6%Aura 2 En — 569 ms, 2.1%Chirp 3 HD — 597 ms, 1.5%Qwen3 TTS Flash Realtime — 718 ms, 3.0%S2.1 Pro Free — 850 ms, 1.5%GPT-4o mini TTS — 2585 ms, 1.8%vui — 59 ms, 2.1%

Where the errors come from

WER compositionvui's Word Error Rate split by error type · 30-day averagevui's WER split into substitutions, deletions and insertions.
  • vui2.1%
SubstitutionsDeletionsInsertions

Averages and tail latency

Averages hide slow outliers — these are the distributions behind each figure.

vui latency distributionMilliseconds · shared axis across metrics · last 30 daysvui's latency percentiles per metric: p25–p75 band, p50 tick, whisker to max.
  • Time to First Audiop50 41 ms · Max 24660 ms
  • TTFA Network Roundtripp50 29 ms · Max 24629 ms
  • TTFA Leading Silencep50 10 ms · Max 75 ms
band p25–p75 · tick p50 · whisker to max with p90 and p95 stops
Average and percentile values per metric, with the number of samples behind each row.
MetricAveragep25p50p75p90p95MaxSamples
Time to First Audio59 ms31 ms41 ms55 ms71 ms82 ms24660 ms1,744
TTFA Network Roundtrip46 ms24 ms29 ms37 ms46 ms54 ms24629 ms1,744
TTFA Leading Silence13 ms0 ms10 ms17 ms37 ms44 ms75 ms1,744
Word Error Rate2.1%0.0%0.0%3.3%10.0%15.0%104.0%1,742

Last 30 days

Daily medians from the same measurement runs · gaps are days without qualifying runs.

Time to First Audio — daily p50Line p50 · band p25–p75 · UTC daysvui's daily median Time to First Audio over the last 30 days.
vui · Sep 23: 64 msvui · Sep 24: 43 msvui · Sep 25: 34 msvui · Sep 26: 60 msvui · Sep 27: 50 msvui · Sep 28: 41 msvui · Sep 29: 75 msvui · Sep 30: 35 msvui · Oct 1: 61 msvui · Oct 2: 33 msvui · Oct 3: 50 msvui · Oct 4: 33 msvui · Oct 5: 48 msvui · Oct 6: 51 msvui · Oct 7: 33 msvui · Oct 8: 40 msvui · Oct 9: 46 msvui · Oct 10: 35 msvui · Oct 11: 44 msvui · Oct 12: 41 msvui · Oct 13: 33 msvui · Oct 14: 49 ms
Word Error Rate — daily averageDaily average · UTC daysvui's daily Word Error Rate over the last 30 days.
vui · Sep 23: 4.7%vui · Sep 24: 4.8%vui · Sep 25: 4.3%vui · Sep 26: 3.4%vui · Sep 27: 4.4%vui · Sep 28: 27.7%vui · Sep 29: 4.1%vui · Sep 30: 3.4%vui · Oct 1: 12.5%vui · Oct 2: 4.6%vui · Oct 3: 3.7%vui · Oct 4: 8.0%vui · Oct 5: 2.9%vui · Oct 6: 5.1%vui · Oct 7: 5.9%vui · Oct 8: 7.1%vui · Oct 9: 3.3%vui · Oct 10: 1.7%vui · Oct 11: 3.1%vui · Oct 12: 5.3%vui · Oct 13: 4.5%vui · Oct 14: 10.9%

How fast is vui?

On Fluxions, vui measures mean 59 ms time to first audio (1st of 32). Last measured 2026-10-14.

How accurate is vui?

On Fluxions, vui measures 2.1% word error rate (27th of 32). Last measured 2026-10-14.

Who hosts vui?

vui is created by Fluxions and served by Fluxions. Coval measures each hosted endpoint separately.

Limits of this comparison

Coval benchmarks the managed API as a named endpoint and reports first-audio timing plus transcript-derived intelligibility.

  • The benchmark does not measure emotional faithfulness, clone similarity or subjective voice preference.

Official sources

Results are re-measured daily using fixed datasets and reported over a rolling 30-day window. Same datasets, prompts and metric definitions for every model, measured by Coval’s open-source runner. Full methodology on the overview.

Evaluate your own voice agent

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