SpaceXAI has released Grok Voice Think Fast 2.0 today， with the High reasoning variant debuting at #2 on the Artificial Analysis Speech to Speech Index at 82.9%， and #1 on Tau Voice for Agentic Performance at 56.5% - among the fastest models at 0.70s Time to First Audio

Grok Voice Think Fast 2.0 is SpaceXAI's successor to Grok Voice Think Fast 1.0 （75.7% on the Speech to Speech Index）. It is the only model in the Index's top five with an average Time to First Audio under 1 second， achieving 0.70 seconds vs. 1.14 seconds for the next fastest， GPT-Realtime-2 High.

Key takeaways： ➤ Speech to Speech Index： Grok Voice Think Fast 2.0 High debuts at #2 at 82.9%， only behind Qwen Audio 3.0 Realtime Plus （84.1%） and ahead of GPT-Realtime-2.1 High （79.1%） and GPT-Realtime-2 High （77.2%）. This is up 7.3 percentage points from Grok Voice Think Fast 1.0 （75.7%） ➤ Speech to Speech Index by Benchmark： On Tau Voice， Grok Voice Think Fast 2.0 High is the new leader at 56.5%， just ahead of Qwen Audio 3.0 Realtime Plus at 54.6% and its predecessor Grok Voice Think Fast 1.0 at 52.1%. On Big Bench Audio， it achieves 97.2%， behind leader Qwen Audio 3.0 Realtime Plus at 99.2%. On our Full Duplex Bench subset， it scores 95.1%， up from 77.8% for Grok Voice Think Fast 1.0， the largest driver of its index gain， behind Qwen Audio 3.0 Realtime Plus at 98.4% ➤ Speed： The model's average Time to First Audio on Big Bench Audio is 0.70 seconds， faster than GPT-Realtime-2 High （1.14s）， GPT-Realtime-2.1 High （1.21s）， and Grok Voice Think Fast 1.0 （1.25s）， and well ahead of Qwen Audio 3.0 Realtime Plus （4.02s） ➤ Price： Grok Voice Think Fast 2.0 is priced at $4.80 per hour of input audio， up from $3.00 for Grok Voice Think Fast 1.0 and more expensive than Qwen Audio 3.0 Realtime Plus （$4.42） and GPT-Realtime-2 High （$4.14）， but ~2.2x cheaper than GPT-Realtime-2.1 High （$10.75）