Google: Gemini 3.1 Flash TTS Brings Expressive AI Speech to More Than 70 Languages

Google has introduced Gemini 3.1 Flash TTS — a new generation text-to-speech model that combines high-quality speech with precise control over voice characteristics. The model achieves an Elo score of 1,211 on the Artificial Analysis TTS leaderboard, placing it at the top among competing solutions.

What Are Audio Tags and Why Do They Change the Game?

The most significant innovation in Gemini 3.1 Flash TTS is audio tags — the ability to embed natural language commands directly into the text being converted to speech. Instead of using complex SSML (Speech Synthesis Markup Language) tags or limited predefined styles, users can describe the desired delivery in plain language.

For example, a user can insert an instruction such as “speak the following sentence in a whisper with a dramatic pause at the end” — and the model will do exactly that. This enables up to 6 luminance zones for voice gradation, giving creatives a level of control that previously required a professional voice actor and an audio studio.

How Broad Is the Language Support?

With support for more than 70 languages, Gemini 3.1 Flash TTS surpasses most competing solutions in language coverage. The model natively supports multi-speaker dialogues — the ability for different characters in a text to have distinct voices without requiring separate API calls for each speaker.

For development teams building global products — from virtual assistants to educational platforms — this means one model instead of separate integrations for each market. Speech quality is consistent across languages, which has traditionally been a challenge for TTS systems.

How Does SynthID Guard Against Misuse?

Google has built SynthID watermarking into the model — a technology for imperceptibly marking AI-generated audio. Every generated audio piece carries a digital marker that enables subsequent detection that the content was created by artificial intelligence, without affecting audio quality.

This is a response to growing concerns about deepfake audio content and voice fraud. SynthID does not prevent generation, but enables authenticity verification — a key tool for platforms, regulators, and journalists.

The model is available on Google AI Studio for experimentation, Vertex AI for production use, and Google Vids for creating video content with an AI narrator.