Voice AI BenchmarksBy

PROVIDERLAST 30 DAYS

official resource

Google voice AI models and benchmarks

Google lists 5 STT, TTS and S2S models in Coval. Fastest dated mean latency over 30 days: STT: Gemini 3.5 Transcribe Live on Gemini at 305 ms TTFS. TTS: Chirp 3 HD at 535 ms TTFA. Coval benchmarks hosted endpoints daily using a consistent evaluation methodology. Last measured .

Google creates and hosts voice models across all three benchmark categories: Cloud Speech-to-Text, Cloud Text-to-Speech and the native-audio Gemini Live API.

Measured models
5
STTTTSS2S
Best STT model#21 / 28
305ms
Gemini 3.5 Transcribe Live
Best TTS model#24 / 28
535ms
Chirp 3 HD

Overview

Google ships voice models across STT, TTS and S2S; each product and generation is ranked separately in its own category.

Every model below is measured daily on the same fixed inputs and ranked against the full field, never blended into a company score.

Model lineup

Speech-to-Text
Gemini 3.5 Transcribe Live, Chirp 2, Chirp 3
Text-to-Speech
Chirp 3 HD
Speech-to-Speech
Gemini 3.1 Flash Live (Preview)

Speech-to-Text

Full STT dashboard

Ranked on Time to Final Segment against 28 measured models.

Time to Final Segmentms · lower is better · Google models markedEvery measured STT model on Time to Final Segment, with Google's models highlighted.
  1. #1Qwen3 ASR 1.7b39 ms
  2. #2Qwen3 ASR Fast46 ms
  3. #3STT RT v557 ms
  4. #4STT 165 ms
  5. #5Parakeet TDT 0.6B v381 ms
  6. #6Nova 389 ms
  7. #7Nova 292 ms
  8. #21Gemini 3.5 Transcribe Live305 ms
  9. #26Chirp 3776 ms
  10. #28Chirp 2873 ms
leaders plus Google models · 18 other models in the full table
Word Error Rate% · lower is better · Google models markedEvery measured STT model on Word Error Rate, with Google's models highlighted.
  1. #1Universal 3.5 Pro3.1%
  2. #2Qwen3 ASR Fast3.2%
  3. #3resonant-13.4%
  4. #4Gemini 3.5 Transcribe Live3.9%
  5. #5Chirp 34.1%
  6. #6Qwen3 ASR 1.7b4.1%
  7. #7Enhanced4.3%
  8. #12Chirp 24.9%
leaders plus Google models · 22 other models in the full table
Time to First Tokenms · lower is better · Google models markedEvery measured STT model on Time to First Token, with Google's models highlighted.
  1. #1Whisper Large v3via Baseten912 ms
  2. #2Qwen3 ASR 1.7b931 ms
  3. #3Universal 3.5 Pro1041 ms
  4. #4Flux1076 ms
  5. #5Flux Multilingual1164 ms
  6. #6Parakeet TDT 0.6B v31215 ms
  7. #7Whisper Large v3via Together AI1338 ms
  8. #16Gemini 3.5 Transcribe Live1679 ms
  9. #25Chirp 35974 ms
  10. #26Chirp 26071 ms
leaders plus Google models · 16 other models in the full table
TTFS vs WER — Google vs every measured modelEach point is one measured STT model · Google models highlighted · 30-day averagesTime to Final Segment against Word Error Rate for every measured STT model, with Google's models highlighted.
Qwen3 ASR 1.7b — 39 ms, 4.1%Qwen3 ASR Fast — 46 ms, 3.2%STT RT v5 — 57 ms, 5.7%STT 1 — 65 ms, 4.4%Parakeet TDT 0.6B v3 — 81 ms, 11.2%Nova 3 — 89 ms, 6.2%Nova 2 — 92 ms, 7.9%Flux Multilingual — 98 ms, 8.8%Flux — 99 ms, 6.7%Ink 2 — 122 ms, 4.8%Whisper Large v3 via Baseten — 125 ms, 5.6%Scribe v2 Realtime — 133 ms, 5.5%Universal 3.5 Pro — 173 ms, 3.1%Grok STT — 207 ms, 4.6%Default via Speechmatics — 209 ms, 5.4%Pulse — 212 ms, 5.3%Default via Gradium — 246 ms, 10.0%resonant-1 — 264 ms, 3.4%Whisper Large v3 via Together AI — 295 ms, 8.5%Enhanced — 299 ms, 4.3%Voxtral Mini Transcribe Realtime 2602 — 401 ms, 6.2%GPT Realtime Whisper — 551 ms, 5.1%GPT-4o mini Transcribe — 690 ms, 4.9%GPT-4o Transcribe — 754 ms, 4.6%Solaria 1 — 805 ms, 7.1%Gemini 3.5 Transcribe Live — 305 ms, 3.9%Chirp 3 — 776 ms, 4.1%Chirp 2 — 873 ms, 4.9%
Benchmarked models with their Time to Final Segment over the last 30 days.
ModelHostTTFSRank
Gemini 3.5 Transcribe LiveGemini305 ms21st of 28
Chirp 2Google873 ms28th of 28
Chirp 3Google776 ms26th of 28

Text-to-Speech

Full TTS dashboard

Ranked on Time to First Audio against 28 measured models.

Time to First Audioms · lower is better · Google models markedEvery measured TTS model on Time to First Audio, with Google's models highlighted.
  1. #1vui66 ms
  2. #2Qwen3 TTS Fast71 ms
  3. #3TTS Flash 291 ms
  4. #4Qwen3 TTS 1.7b106 ms
  5. #5Palabra TTS v1115 ms
  6. #6TTS 2181 ms
  7. #7Flash v2.5194 ms
  8. #24Chirp 3 HD535 ms
leaders plus Google models · 20 other models in the full table
Word Error Rate% · lower is better · Google models markedEvery measured TTS model on Word Error Rate, with Google's models highlighted.
  1. #1TTS RT v13.9%
  2. #2TTS Rt v24.2%
  3. #3Qwen3 TTS Fast4.2%
  4. #4Eleven v3 Conversational4.4%
  5. #5Lightning v3.1 Pro4.4%
  6. #6Simba 3.24.4%
  7. #7TTS 24.6%
  8. #14Chirp 3 HD5.2%
leaders plus Google models · 20 other models in the full table
TTFA vs WER — Google vs every measured modelEach point is one measured TTS model · Google models highlighted · 30-day averagesTime to First Audio against Word Error Rate for every measured TTS model, with Google's models highlighted.
vui — 66 ms, 5.4%Qwen3 TTS Fast — 71 ms, 4.2%TTS Flash 2 — 91 ms, 5.4%Qwen3 TTS 1.7b — 106 ms, 5.5%Palabra TTS v1 — 115 ms, 5.8%TTS 2 — 181 ms, 4.6%Flash v2.5 — 194 ms, 6.7%Default — 235 ms, 5.3%TTS Rt v2 — 245 ms, 4.2%TTS RT v1 — 245 ms, 3.9%Mist v3 — 258 ms, 5.5%Sonic 3.5 — 277 ms, 5.9%Phantom Z 3.4 conversational — 286 ms, 6.0%Aura 2 — 308 ms, 5.2%Coda — 312 ms, 5.0%S2.1 Pro — 335 ms, 4.8%Eleven v3 Conversational — 348 ms, 4.4%Lightning v3.1 Pro — 362 ms, 4.4%S1 — 379 ms, 4.9%Grok TTS — 397 ms, 4.9%Sonic 3.6 — 423 ms, 5.3%Simba 3.2 — 451 ms, 4.4%Simba 3.0 — 472 ms, 5.2%Falcon 2 — 545 ms, 5.2%Qwen3 TTS Flash Realtime — 753 ms, 8.9%S2.1 Pro Free — 963 ms, 4.7%GPT-4o mini TTS — 1013 ms, 4.8%Chirp 3 HD — 535 ms, 5.2%
Benchmarked models with their Time to First Audio over the last 30 days.
ModelHostTTFARank
Chirp 3 HDGoogle535 ms24th of 28

Speech-to-Speech

Full S2S dashboard

Ranked on Voice-to-Voice Latency.

Benchmarked models with their Voice-to-Voice Latency over the last 30 days.
ModelHostV2VRank
Gemini 3.1 Flash Live (Preview)Googleno measurements this window

How fast are Google's STT, TTS and S2S models?

Gemini 3.5 Transcribe Live on Gemini measures mean 305 ms time to final segment (21st of 28) among STT systems. Last measured 2026-09-15. Chirp 3 measures mean 776 ms time to final segment (26th of 28) among STT systems. Last measured 2026-09-15. Chirp 2 measures mean 873 ms time to final segment (28th of 28) among STT systems. Last measured 2026-09-15. Chirp 3 HD measures mean 535 ms time to first audio (24th of 28) among TTS systems. Last measured 2026-09-15. No dated, ranked S2S latency is available in this window.

How accurate are Google's STT, TTS and S2S models?

Gemini 3.5 Transcribe Live on Gemini measures 3.9% word error rate (4th of 30) among STT systems. Last measured 2026-09-15. Chirp 3 measures 4.1% word error rate (5th of 30) among STT systems. Last measured 2026-09-15. Chirp 2 measures 4.9% word error rate (12th of 30) among STT systems. Last measured 2026-09-15. Chirp 3 HD measures 5.2% word error rate (14th of 28) among TTS systems. Last measured 2026-09-15. No dated, ranked S2S instruction adherence is available in this window.

Which Google model is fastest?

Its fastest dated STT result is Gemini 3.5 Transcribe Live on Gemini at mean 305 ms time to final segment (21st of 28) among STT systems, with 3.9% WER. Last measured 2026-09-15. Its fastest dated TTS result is Chirp 3 HD at mean 535 ms time to first audio (24th of 28) among TTS systems, with 5.2% WER. Last measured 2026-09-15.

Limits of this comparison

  • The measured endpoints do not represent every Google Cloud region, Chirp voice, Gemini capability or language.

Official resources

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

Use Coval to test your production configuration, prompts and calls—not only the public benchmark endpoints.

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