Voice AI BenchmarksBy

PROVIDERLAST 30 DAYS

official resource

SpaceXAI voice AI models and benchmarks

SpaceXAI lists 2 STT and TTS models in Coval. Fastest dated mean latency over 30 days: STT: Grok STT at 223 ms TTFS, with 4.1% WER. TTS: Grok TTS at 362 ms TTFA, with 1.6% WER. Coval benchmarks hosted endpoints daily using a consistent evaluation methodology. Last measured .

SpaceXAI provides Grok-branded speech recognition and synthesis APIs.

Measured models
2
STTTTS
Best STT model#17 / 29
223ms
Grok STT
Best TTS model#24 / 32
362ms
Grok TTS

Overview

SpaceXAI spans both the input and output stages, with multilingual support and additional voice controls across the active Grok services.

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
Grok STT
Text-to-Speech
Grok TTS

Speech-to-Text

Full STT dashboard

Ranked on Time to Final Segment against 29 measured models.

Time to Final Segmentms · lower is better · SpaceXAI models markedEvery measured STT model on Time to Final Segment, with SpaceXAI's models highlighted.
  1. #1Qwen3 ASR 1.7b39 ms
  2. #2STT RT v545 ms
  3. #3Qwen3 ASR Fast47 ms
  4. #4STT 167 ms
  5. #5Nova 385 ms
  6. #6Nova 287 ms
  7. #7Parakeet TDT 0.6B v397 ms
  8. #17Grok STT223 ms
leaders plus SpaceXAI models · 21 other models in the full table
Word Error Rate% · lower is better · SpaceXAI models markedEvery measured STT model on Word Error Rate, with SpaceXAI's models highlighted.
  1. #1Universal 3.6 Pro2.1%
  2. #2Universal 3.5 Pro2.3%
  3. #3Qwen3 ASR Fast2.6%
  4. #4resonant-12.6%
  5. #5Qwen3 ASR 1.7b2.9%
  6. #6Gemini 3.5 Transcribe Live3.0%
  7. #7Chirp 33.2%
  8. #14Grok STT4.1%
leaders plus SpaceXAI models · 23 other models in the full table
Time to First Tokenms · lower is better · SpaceXAI models markedEvery measured STT model on Time to First Token, with SpaceXAI's models highlighted.
  1. #1Whisper Large v3via Baseten924 ms
  2. #2Qwen3 ASR 1.7b946 ms
  3. #3Universal 3.5 Pro1026 ms
  4. #4Universal 3.6 Pro1072 ms
  5. #5Flux1091 ms
  6. #6Flux Multilingual1165 ms
  7. #7STT 11208 ms
leaders plus SpaceXAI models · 20 other models in the full table
TTFS vs WER — SpaceXAI vs every measured modelEach point is one measured STT model · SpaceXAI models highlighted · 30-day averagesTime to Final Segment against Word Error Rate for every measured STT model, with SpaceXAI's models highlighted.
Qwen3 ASR 1.7b — 39 ms, 2.9%STT RT v5 — 45 ms, 4.8%Qwen3 ASR Fast — 47 ms, 2.6%STT 1 — 67 ms, 7.1%Nova 3 — 85 ms, 5.3%Nova 2 — 87 ms, 6.7%Parakeet TDT 0.6B v3 — 97 ms, 11.1%Flux Multilingual — 98 ms, 7.5%Flux — 99 ms, 5.8%Scribe v2 Realtime — 122 ms, 4.4%Whisper Large v3 via Baseten — 131 ms, 4.5%Universal 3.6 Pro — 135 ms, 2.1%Ink 2 — 149 ms, 3.6%Universal 3.5 Pro — 168 ms, 2.3%Whisper Large v3 via Together AI — 199 ms, 7.4%Pulse — 205 ms, 4.6%resonant-1 — 252 ms, 2.6%Default — 258 ms, 8.8%Linden 1 — 271 ms, 3.9%Gemini 3.5 Transcribe Live — 317 ms, 3.0%Daytona STT — 399 ms, 4.9%Voxtral Mini Transcribe Realtime 2602 — 411 ms, 5.3%GPT Realtime Whisper — 599 ms, 4.0%Solaria 1 — 626 ms, 6.0%GPT-4o mini Transcribe — 708 ms, 3.9%Chirp 3 — 768 ms, 3.2%GPT-4o Transcribe — 783 ms, 3.7%Chirp 2 — 908 ms, 3.9%Grok STT — 223 ms, 4.1%
Benchmarked models with their Time to Final Segment over the last 30 days.
ModelHostTTFSRank
Grok STTSpaceXAI223 ms17th of 29

Text-to-Speech

Full TTS dashboard

Ranked on Time to First Audio against 32 measured models.

Time to First Audioms · lower is better · SpaceXAI models markedEvery measured TTS model on Time to First Audio, with SpaceXAI's models highlighted.
  1. #1vui60 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 TTS v1120 ms
  8. #24Grok TTS362 ms
leaders plus SpaceXAI models · 24 other models in the full table
Word Error Rate% · lower is better · SpaceXAI models markedEvery measured TTS model on Word Error Rate, with SpaceXAI's models highlighted.
  1. #1Sonic 3.61.5%
  2. #2S2.1 Pro Free1.5%
  3. #3Simba 3.01.5%
  4. #4S2.1 Pro1.5%
  5. #5Lightning v3.1 Pro1.5%
  6. #6Sonic 3.51.5%
  7. #7Chirp 3 HD1.5%
  8. #8Grok TTS1.6%
leaders plus SpaceXAI models · 24 other models in the full table
TTFA vs WER — SpaceXAI vs every measured modelEach point is one measured TTS model · SpaceXAI models highlighted · 30-day averagesTime to First Audio against Word Error Rate for every measured TTS model, with SpaceXAI's models highlighted.
vui — 60 ms, 2.1%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 v1 — 120 ms, 2.6%Simba 3.2 — 126 ms, 1.9%drama3-preview — 168 ms, 2.0%TTS 2 — 191 ms, 1.6%Flash v2.5 — 191 ms, 1.8%Eleven v4 Turbo — 201 ms, 1.7%Flux TTS — 205 ms, 1.7%TTS RT v1 — 254 ms, 2.4%TTS Rt v2 — 256 ms, 2.4%Mist v3 — 287 ms, 2.1%Sonic 3.5 — 293 ms, 1.5%Phantom Z 3.4 conversational — 293 ms, 1.8%Aura 2 — 297 ms, 1.8%Sonic 3.6 — 299 ms, 1.5%Falcon 2 — 301 ms, 1.7%Coda — 332 ms, 9.5%S2.1 Pro — 341 ms, 1.5%S1 — 389 ms, 1.8%Lightning v3.1 Pro — 393 ms, 1.5%Daytona TTS — 486 ms, 1.6%Aura 2 En — 570 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 — 2581 ms, 1.8%Grok TTS — 362 ms, 1.6%
Benchmarked models with their Time to First Audio over the last 30 days.
ModelHostTTFARank
Grok TTSSpaceXAI362 ms24th of 32

How fast are SpaceXAI's STT and TTS models?

Grok STT measures mean 223 ms time to final segment (17th of 29) among STT systems. Last measured 2026-10-14. Grok TTS measures mean 362 ms time to first audio (24th of 32) among TTS systems. Last measured 2026-10-14.

How accurate are SpaceXAI's STT and TTS models?

Grok STT measures 4.1% word error rate (14th of 31) among STT systems. Last measured 2026-10-14. Grok TTS measures 1.6% word error rate (8th of 32) among TTS systems. Last measured 2026-10-14.

Which SpaceXAI model is fastest?

Its fastest dated STT result is Grok STT at mean 223 ms time to final segment (17th of 29) among STT systems, with 4.1% WER. Last measured 2026-10-14. Its fastest dated TTS result is Grok TTS at mean 362 ms time to first audio (24th of 32) among TTS systems, with 1.6% WER. Last measured 2026-10-14.

Limits of this comparison

Coval measures the company's first-party STT and TTS endpoints independently.

  • The benchmark does not combine the endpoints into an agent or score every Grok voice and expressive capability.

Official resources

Same datasets, prompts and metric definitions for every model, measured by Coval’s open-source runner. Full methodology on the overview.

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