Google launched two new text-to-speech models that let developers create custom voices from scratch and control delivery line-by-line, with the premium version ranking first on voice customization benchmarks. The models include safeguards like consent verification for voice replication and SynthID watermarking to detect AI-generated speech.

• Gemini 3.8 Flash TTS lets you generate entirely new voices using natural language prompts, customize 2,000+ existing voices, or replicate a voice from a 30-second sample with built-in consent checks.
• Both models rank #1 and #2 on Hume AI's Overall Quality Index and support 100+ languages with strong performance in Japanese, Brazilian Portuguese, Vietnamese, Arabic, Spanish, and Hindi.
• You can direct performance line-by-line with stage directions, maintain voice consistency across hours of audio, stage two-speaker conversations, and add realistic conversational sounds like laughs and sighs.
• Every generated audio is watermarked with SynthID to remain detectable as AI-generated, and the models are rolling out today to developers via Gemini API and Google AI Studio.