Google Ships Gemini 3.8 Live and Live Extended Thinking for Voice Agents
On September 15, 2026, Google launched Gemini 3.8 Live and 3.8 Live Extended Thinking, native speech-to-speech models for the Live API, Search Live, Gemini Live, and Workspace. Extended Thinking takes Artificial Analysis’ Speech-to-Speech Quality Index at 82.6.
TLDR
Google on Tuesday, September 15, 2026 published Gemini 3.8 Live and Gemini 3.8 Live Extended Thinking—native speech-to-speech models for production voice agents. 3.8 Live: scale and cost, visual grounding, background tool calls, auto-detect 97 languages. 3.8 Live Extended Thinking: high-complexity tasks; reasons and speaks at once. Independent: Extended Thinking #1 on Artificial Analysis Speech to Speech Quality Index (82.6); τ-Voice 68.6%; Sierra τ-Voice-banking 35.1%; Big Bench Audio 97.7%. Base 3.8 Live second on AA Speech Agent Arena. Dev: Gemini API + AI Studio Live API at $0.005/min audio in, $0.018/min out. Enterprise private preview in Gemini Enterprise. Consumer: 3.8 Live powers Search Live; Extended Thinking in Gemini Live and, for AI Pro / Ultra, Docs / Gmail / Keep. SynthID on all generated audio.
Two SKUs
| SKU | Job | Where it ships today |
|---|---|---|
| 3.8 Live | Low-latency dialogue + visual + async tools | API, AI Studio, Search Live, Gemini Enterprise (private preview) |
| 3.8 Live Extended Thinking | Multi-step reasoning while speaking | API, AI Studio, Gemini Live, Docs/Gmail/Keep (Pro/Ultra) |
Ranking: lab cites Artificial Analysis (82.6 #1 S2S Quality Index; Arena #2 for base Live) plus τ-Voice, Sierra banking, Big Bench Audio. EVA-Bench (ServiceNow): Google says the pair sit on the accuracy–quality Pareto. SiliconANGLE’s AA snapshot names GPT-Live-1-Astra and Grok Voice Think Fast 2.0 as the models it surpassed—do not treat that as an Arena Elo.
Product-line de-dupe: not Gemini 3.8 Flash / Flash Cyber (Sep 2), not 3.1 Flash Live (March), not 3.5 Transcribe (last month; 85+ languages, WER 4.0% streaming). Distinct from unfiled OpenAI GPT-Live-1 API (Sep 10 re-pass).
Why this story matters
Google is putting live speech on the same 3.8 family as Flash, and it is claiming the independent S2S board, not just a vendor table. Watch: whether Search Live actually sounds like Extended Thinking, and whether $0.005 / $0.018 holds once GPT-Live-1 is in the API.