Gemini 3.1 Flash TTS: the next generation of expressive AI speech

Introduces Gemini 3.1 Flash TTS, a new text-to-speech model with improved speech quality, controllability, and expressivity. Key technical contributions include: 1. Enhanced speech quality, achieving an Elo score of 1,211 on the Artificial Analysis TTS leaderboard. 2. Introduction of 'audio tags' for granular control over vocal style, pace, and delivery via natural language commands embedded in text input. 3. New developer experience features in Google AI Studio: scene direction for environmental context and dialogue instructions, speaker-level specificity with Audio Profiles and Director's Notes for pace, tone, and accent, and inline tags for mid-sentence expression changes. 4. Support for 70+ languages with advanced style, pacing, and accent control for localized experiences. 5. Audio watermarking with SynthID for reliable detection of AI-generated content.