CL-SN55 941 —
GPT-61S 885 —
GPT-56T 861 —
GPT-6S 825 —
CL-OP55X 818 -0.1%
MUSE-SPK 793 —
QWEN-38X 779 —
GPT-6A 778 —
CL-OP5H 711 -0.1%
CL-OP5X 709 -0.1%
KIMI-K3X 699 -0.1%
CL-OP46H 694 -0.1%
CL-FAB5H 692 -0.1%
CL-OP55H 692 -0.1%
CL-OP47H 683 -0.1%
GEM-37FH 648 -0.2%
GEM-38FH 633 -0.2%
INKL 531 —
CL-OP47 529 -0.2%
GPT-56S 529 -5.9%
GEM-3P 493 —
CL-OP46 488 —
CL-OP48 481 —
GEM-31P 453 -0.2%
GPT-6L 436 —
CL-SN55 941 —
GPT-61S 885 —
GPT-56T 861 —
GPT-6S 825 —
CL-OP55X 818 -0.1%
MUSE-SPK 793 —
QWEN-38X 779 —
GPT-6A 778 —
CL-OP5H 711 -0.1%
CL-OP5X 709 -0.1%
KIMI-K3X 699 -0.1%
CL-OP46H 694 -0.1%
CL-FAB5H 692 -0.1%
CL-OP55H 692 -0.1%
CL-OP47H 683 -0.1%
GEM-37FH 648 -0.2%
GEM-38FH 633 -0.2%
INKL 531 —
CL-OP47 529 -0.2%
GPT-56S 529 -5.9%
GEM-3P 493 —
CL-OP46 488 —
CL-OP48 481 —
GEM-31P 453 -0.2%
GPT-6L 436 —
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Gemini 3.8 Flash TTS Claims #1 on Hume AI Voice Benchmark with 71.4, Adds 2,000-Voice Library

Google launched two new text-to-speech models on September 23: Gemini 3.8 Flash TTS and Gemini 3.8 Flash-Lite TTS. Both are live now via Gemini API and Google AI Studio.

Benchmark position

  • Hume AI Voice Design Benchmark: 71.4 (#1 overall)
  • Accent modeling: 60.8 (#1)
  • Hume AI Overall Quality Index: #1 (Flash TTS) and #2 (Flash-Lite TTS)
  • Voice Arena: top positions in Japanese, Brazilian Portuguese, Vietnamese, MSA Arabic, Mexican Spanish, and Hindi

Gemini 3.1 Flash TTS launched in April 2026 with 30 preset voices and 70+ language support. The 3.8 generation replaces that preset model with generative voice design.

What changed from 3.1

  • Generative voice design: describe a character in natural language and the model creates a matching voice from scratch, across 100+ languages and dialects
  • Voice library: 2,000+ production-ready voices, including regional variants such as Mexican Spanish, Quebec French, and Scots English
  • Voice replication: reconstruct a consistent vocal profile from a 30-second audio sample, backed by SynthID watermarking and C2PA credentials for consent verification
  • Line-level direction: control acting cues, pacing, dialect shifts, and backchanneling on individual lines of a script

Flash-Lite TTS

The lighter model targets high-volume pipelines: dubbing, voice agent infrastructure, and content creation at scale. Google positions it as cost-efficient rather than creatively expressive, with fine-grained tone and pacing controls but without the full generative voice-design stack.

Availability

  • Developers: Gemini API and Google AI Studio (live now)
  • Enterprises: Gemini Enterprise API (coming soon)
  • Products: Gemini Notebook and Google Vids (shipping with the new models)

The 3.8 TTS pair extends Google’s audio push that began with Gemini 3.5 Live Translate, 3.5 Transcribe, and 3.8 Live earlier this year. Voice generation is now a direct competitive front between labs alongside coding and reasoning.