Gemini 3.1 Flash TTS: AI Audio Generator

Turn dialogue into expressive multi-speaker speech with Gemini 3.1 Flash TTS. Control voice, accent, emotion, and pace. Try free, pay per use.

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Overview

About this model

Gemini 3.1 Flash TTS is Google's fast, cost-efficient text-to-speech model for expressive multi-speaker audio. Define any number of speakers, each with a distinct voice, accent, emotional style, and pace, then script a conversation across ordered dialogue turns with inline tone tags like [whispers] or [shouting]. It is ideal for character dialogue, game and video voiceovers, podcasts, and narration where you need natural delivery at speed and scale. For the highest-fidelity studio output, see Gemini 2.5 Pro TTS.

1Games & Interactive: Voice NPCs and branching dialogue with distinct, emotionally-directed characters.
2Video & Shorts: Generate fast, affordable voiceovers and character lines for content production.
3Podcasts: Produce multi-host conversational audio from a written script.
4Prototyping: Iterate quickly on tone, accent, and pacing before a final high-fidelity render.
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Pricing & Value

Cost analysis

muapiapp$0.035 per 1,000 characters

Pay per generation, no subscription. Full multi-speaker control included.

Fal.aiNot available

Does not offer this model.

ReplicateNot available

Does not offer this model.

* Competitor pricing is estimated based on similar model architectures and usage tiers.

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Technical Details

Configuration schema

Speakersarray

List of speaker voice configurations. Each dialogue turn references a speaker by its ID.

Default Value[object Object],[object Object]
Dialogue Turnsarray

Ordered list of dialogue lines. Each turn's speaker_id must match a speaker defined above. Text may include tone tags like [shouting] or [whispers].

Default Value[object Object],[object Object],[object Object],[object Object]
Scenestring

Optional scene description that sets the acoustic setting, e.g. "A quiet, warm room with a fireplace crackling softly."

Default Value
Sample Contextstring

Optional overall tone/style, e.g. "Audiobook style narration. Tone is gentle and inviting."

Default Value
Temperaturenumber

Sampling temperature (0-2). Higher values produce more varied delivery.

Default Value1
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Implementation Guide

Developer documentation

How to Use Gemini 3.1 Flash TTS

  1. Define your speakers: Add one entry per voice to the speakers list. Give each a speaker_id in "Speaker N" format, pick a voice_name, and set the accent, style, and pace. Optionally add an audio_profile describing the persona.

  2. Write the dialogue: Fill dialogue_turns with ordered lines. Each turn's speaker_id must match a speaker you defined. You can embed tone tags inline such as [whispers], [shouting], or [determination].

  3. Set the mood (optional): Use scene to describe the acoustic setting and sample_context to set the overall narration tone. Adjust temperature (0-2) for more or less varied delivery.

  4. Submit and poll: POST the request, then poll /predictions/{request_id}/result until the status is completed to get the audio URL.

curl -X POST https://api.muapi.ai/api/v1/gemini-3-1-flash-tts \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "speakers": [
      {"speaker_id": "Speaker 1", "voice_name": "Fenrir", "accent": "British (RP)", "style": "Deadpan", "pace": "Natural"},
      {"speaker_id": "Speaker 2", "voice_name": "Puck", "accent": "American (Gen)", "style": "Empathetic", "pace": "Staccato"}
    ],
    "dialogue_turns": [
      {"speaker_id": "Speaker 1", "text": "[shouting] Halt, traveler!"},
      {"speaker_id": "Speaker 2", "text": "[determination] I carry a message for the elder."}
    ],
    "scene": "A dark, crumbling dungeon.",
    "temperature": 1
  }'

Common Questions

Frequently asked

How do I create a multi-speaker conversation?

Define each voice in the `speakers` list with a unique `speaker_id` (in "Speaker N" format), then reference those IDs in your `dialogue_turns`. The model renders each line in that speaker's assigned voice, accent, style, and pace.

Can I control emotion and pacing?

Yes. Each speaker has `style` (Vocal Smile, Newscaster, Whisper, Empathetic, Promo/Hype, Deadpan) and `pace` (Natural, Rapid Fire, The Drift, Staccato) settings. You can also embed inline tone tags like [whispers], [shouting], or [determination] directly in the dialogue text.

What voices and accents are available?

There are 30 prebuilt voices (Zephyr, Fenrir, Puck, Kore, and more) and 8 accents including Neutral, American variants, British (RP), British (Brixton), Transatlantic, and Australian.

How is pricing calculated?

Pricing is based on the total number of characters across all dialogue turns, at $0.035 per 1,000 characters. You pay per generation with no subscription.

What is the maximum length per line?

Each dialogue turn's text can be up to 10,000 characters. You can include multiple turns to build longer conversations.

What is the difference between the Flash and Pro versions?

Gemini 3.1 Flash TTS is optimized for fast, cost-efficient generation, while Gemini 2.5 Pro TTS targets premium studio-quality, high-fidelity output. Both share the same multi-speaker controls.