Gemini 3.8 TTS reaches GA and adds voice remixing

Google has made Gemini 3.8 Flash TTS and Gemini 3.8 Flash-Lite TTS generally available through the Gemini API. The release also adds the Voices endpoint, /v1beta/voices, for discovering and using prebuilt and custom voices.

Two models for different voice workloads

gemini-3.8-flash-tts is the flagship creative model. Google describes it as engineered for studio-grade voice fidelity, nuanced acting, regional dialects, and long-form multi-turn stability.

gemini-3.8-flash-lite-tts is the faster, cost-efficient option. Google positions it as a replacement for gemini-3.1-flash-tts-preview in high-throughput production and real-time voice-agent cascades.

Custom voices and the Voices endpoint

The GA release adds voice design from text prompts, voice replication with consent verification, and access to more than 150 prebuilt and custom voices. The endpoint gives applications a way to query that voice library instead of hard-coding a single voice into every integration.

Voice selection is only one part of a reliable voice agent. Test pronunciation, interruption behavior, latency, consent records, fallback behavior, and how generated audio is disclosed to users before expanding a custom persona to production.

Migration checklist

Teams moving from the preview TTS model should test the new model IDs and confirm account access, quotas, and pricing in the current Gemini API documentation. Compare Flash TTS and Flash-Lite TTS on the same scripts and interaction traces; the most expressive voice is not always the best choice for a high-volume or low-latency workflow.

September 29 follow-up: Flash-Lite TTS in Google Vids

Google says Gemini 3.8 Flash-Lite TTS now powers AI voiceovers and avatar narration in Google Vids. The Workspace update describes more natural sentence flow, lifelike pacing, context-aware emphasis, and faster generation for script iteration and real-time previews. Google listed the feature as available for Rapid Release and Scheduled Release domains at announcement time and said there is no separate admin control or end-user setting. Its published eligibility list includes supported Business, Enterprise, Education, consumer, and add-on editions; check the current Workspace notice for the exact plan list. (https://workspaceupdates.googleblog.com/2026/09/create-more-natural-expressive-ai-voiceovers-in-Google-Vids-with-upgraded-Gemini-3.8-Flash-Lite-TTS.html)

November 4 follow-up: voice remixing

Google’s Gemini API changelog says voice remixing is now available for Gemini 3.8 Flash TTS. Developers can use natural-language instructions to modify an existing prebuilt or designed voice and create a separate stored voice with its own voice ID. The changelog points to POST /v1beta/voices with gemini-3.8-flash-tts; the resulting voice ID can be used for synthesis with Gemini 3.8 Flash TTS or Flash-Lite TTS. (https://ai.google.dev/gemini-api/docs/changelog; https://ai.google.dev/docs/voice-remixing)

Review the current voice-remixing guide for supported inputs and requirements before using the feature in a product.

Sources

• Google AI for Developers — Gemini API release notes (September 22, 2026): https://ai.google.dev/gemini-api/docs/changelog
• Google AI for Developers — Gemini API changelog text: https://ai.google.dev/gemini-api/docs/changelog.md.txt
• Google AI for Developers — Voice remixing: https://ai.google.dev/docs/voice-remixing
• Google Workspace Updates — Gemini 3.8 Flash-Lite TTS in Google Vids (September 29, 2026): https://workspaceupdates.googleblog.com/2026/09/create-more-natural-expressive-ai-voiceovers-in-Google-Vids-with-upgraded-Gemini-3.8-Flash-Lite-TTS.html
• Google for Developers on X — official developer updates: https://x.com/googledevs