# Grok Voice Think Fast 2.0: AA Speech Lead—and an Aug 5 Default Cutover

Times of AI Desk · 2026-07-29 · Models

[https://timesof.ai/2026/07/spacexai-grok-voice-think-fast-2](https://timesof.ai/2026/07/spacexai-grok-voice-think-fast-2)

> xAI’s Grok Voice Think Fast 2.0 cites Artificial Analysis speech-to-speech quality at 82.9% (ahead of GPT-Realtime-2.1 High at 79.1%), 0.70s time-to-first-audio, and $0.08/min. grok-voice-latest migrates to 2.0 on August 5 unless pinned—force a pin strategy before the default flips.

Voice is becoming a **primary enterprise surface** for support, sales, and agent workflows—not a demo. Shipping a measurable step on third-party speech-to-speech boards **and** a dated default API migration forces teams to re-evaluate cost, latency, and pin strategy before August 5.

**xAI** announced **Grok Voice Think Fast 2.0**, its most capable **speech-to-speech** voice model. The company primary cites **Artificial Analysis** leadership on speech-to-speech quality (**82.9%** vs **79.1%** for GPT-Realtime-2.1 High), **0.70s** time to first audio (down from **1.25s** on 1.0), roughly **0.4×** the reasoning tokens of its predecessor in production, and **$0.08 per minute** of audio. **`grok-voice-latest`** migrates to 2.0 on **August 5, 2026** unless pinned.

## What shipped

| Item | Detail (x.ai primary) |
|------|------------------------|
| **Model** | **Grok Voice Think Fast 2.0** |
| **Focus** | Speech reasoning, transcription accuracy, conversational tool use |
| **AA Speech-to-Speech Quality** | **82.9%** (1.0: 75.7%; GPT-Realtime-2.1 High: 79.1%) |
| **tau-Voice agentic** | **56.5%** vs **45.7%** for GPT-Realtime-2.1 High (lab table) |
| **Latency** | **0.70s** time to first audio (1.0: 1.25s) |
| **Pricing** | **$0.08 / min** of audio |
| **Default cutover** | **`grok-voice-latest` → 2.0 on Aug 5, 2026** (pin `grok-voice-think-fast-1.0` to stay) |
| **Production claim** | A/B on **Starlink** support/sales lines: higher conversion and containment |

xAI positions 2.0 as reasoning **while speaking**—tool calls often fire before the first sentence finishes—without adding turn-taking latency. Transcription claims include **1.5–2.0×** lower word-error relative to Deepgram Nova 3 and ElevenLabs Scribe v2 on internal multilingual short-phrase tests, with larger gaps under noise/telephony compression.

## Independent rankings

| Source | Metric | Snapshot |
|--------|--------|----------|
| **Artificial Analysis** Speech-to-Speech | Quality Index **82.9%** | Cited on x.ai launch post as leading GPT-Realtime-2.1 High (**79.1%**) and Gemini 3.1 Flash High (**69.5%**) |
| **AA / lab tau-Voice** | Agentic voice **56.5%** | Lab table vs **45.7%** (GPT-Realtime-2.1 High) |

Distinct from **Grok 4.5** (text/coding flagship), **Build Mode**, and **Imagine** media models. Continues the **Voice Agent API / Think Fast** line (1.0 earlier in 2026). Competes with **OpenAI GPT-Live / Realtime** and **Google Gemini** voice stacks.

## Limits

- tau-Voice and WER comparisons vs Deepgram/ElevenLabs are lab tables.
- Starlink A/B conversion/containment is production claim, not a public third-party study.
- Pin `grok-voice-think-fast-1.0` before Aug 5 if you need the prior SKU.

## Sources

- [xAI: Introducing Grok Voice Think Fast 2.0 (July 29, 2026)](https://x.ai/news/grok-voice-think-fast-2)
- [Artificial Analysis Speech-to-Speech](https://artificialanalysis.ai/speech-to-speech)
- [xAI Voice / speech-to-speech docs](https://docs.x.ai/developers/model-capabilities/audio/speech-to-speech)