Gemini 3.1 Flash TTS is Google’s new text-to-speech model, now available in preview through the Gemini API, Google AI Studio, and Vertex AI.
The problem:
TTS APIs have always treated voice as a static output.
You pick up the sound, set the speed, and the model delivers a flat read.
Expressive means engineering work or accepting robotic delivery.
Solution:
Gemini 3.1 Flash TTS introduces Audio Tags natural language commands that are embedded directly into text input to control tone, pacing, accent, and expression mid-sentence.
You can define scene contexts, cast multiple speakers with unique sound profiles, and export complete configurations as API code for continuous reuse across projects.
What stands out?:
🎙 Inline audio tags mean you can change tone, pacing, and delivery mid-sentence without having to re-cue.
🗣 Native multi-speaker dialog means you can cast and direct multiple characters in a single API call
🌍 70+ language support with per-locale accent control means you can localize expressive speech without a separate pipeline
📤 Exportable voice configuration means your character and delivery style stays the same in every project.
🔒 SynthID watermarking means every output is attributed out of the AI-generated box
Who is it for?:
Developers and product teams building voice agents, AI dubbing tools, interactive storytelling apps, and multilingual content platforms that need expressive, controllable speech at scale.