If you are asking what is Gemini 3.1 Flash TTS, the short answer is that it is Google’s preview text-to-speech model in the Gemini API for turning text into expressive, steerable, multilingual audio. It is built for developers and teams that want more control than basic voice synthesis usually provides, including control over tone, pace, accent, narration style, and even simple two-speaker dialogue.
This guide uses the official Gemini 3.1 Flash TTS model page, Google’s speech generation documentation, and Gemini API release notes as the main references. Google launched Gemini 3.1 Flash TTS Preview on April 15, 2026, and positions it as a cost-efficient, low-latency speech model with improvements to naturalness, controllability, and multilingual output.
What is Gemini 3.1 Flash TTS in simple terms? A Google speech model for reading your script out loud the way you want it performed.
7 key facts at a glance
What is Gemini 3.1 Flash TTS at a glance? It is Google’s latest preview text-to-speech model for controllable audio generation in the Gemini API.
- Gemini 3.1 Flash TTS is a preview model designed specifically for text-to-speech generation.
- It accepts text input and returns audio output, rather than text or multimodal responses.
- Google says the model supports both single-speaker and two-speaker audio generation.
- It introduces expressive audio tags and natural-language prompting for controlling style, pacing, and delivery.
- Google provides 30 prebuilt voice options and broad multilingual support with automatic language detection.
- The model supports Batch API workflows, but it does not support Live API, function calling, structured outputs, or search grounding.
- Google also documents practical limits, including no streaming support, possible output drift on longer clips, and the need for retry logic in some applications.
Why Gemini 3.1 Flash TTS matters
Gemini 3.1 Flash TTS matters because many teams do not just want speech output. They want speech output that sounds usable in production. That usually means natural delivery, faster turnaround, multilingual coverage, predictable prompting, and enough control to shape how a line is performed instead of accepting one generic reading.
That matters for voiceovers, tutorials, customer support flows, product demos, training content, automated narration, and podcast-style clips. It also matters for teams trying to turn voice generation into a repeatable operating system instead of a one-off experiment. If you are thinking in that direction, Progressive Robot’s guide to workflow automation is useful context for how AI tools become production workflows instead of isolated tests.
What is Gemini 3.1 Flash TTS in simple terms
What is Gemini 3.1 Flash TTS in plain English? It is a Gemini API model that takes written text and performs it as speech.
That sounds simple, but the important distinction is control. Gemini 3.1 Flash TTS is not just reading words mechanically. Google’s documentation focuses on steerability, which means developers can guide how the speech sounds with natural language directions, inline audio tags, and more detailed prompt structures that resemble creative direction.
So what is Gemini 3.1 Flash TTS really for? It is for cases where you already know the words you want spoken and want Google to generate audio that sounds more deliberate, more human, and more tailored to the context.
How Gemini 3.1 Flash TTS fits into Google's audio stack
What is Gemini 3.1 Flash TTS inside Google’s broader audio story? It is Google’s dedicated scripted speech-generation model, separate from the Live API’s real-time conversational audio models.
1. Gemini 3.1 Flash TTS is a dedicated TTS model, not a live conversation model
The first thing to understand about Gemini 3.1 Flash TTS is that it is built for exact text recitation. Google’s speech-generation docs draw a clear distinction between Gemini TTS and the Live API. The Live API is for interactive, unstructured, real-time audio experiences. Gemini TTS is for scenarios where you want a known transcript spoken aloud with fine-grained control.
That makes Gemini 3.1 Flash TTS a better fit for voiceovers, scripted dialogue, podcast intros, lessons, announcements, training assets, or narrated product content than for real-time back-and-forth voice assistants.
2. Gemini 3.1 Flash TTS is built around controllable performance
Google’s current model page says Gemini 3.1 Flash TTS introduces expressive audio tags and improves naturalness, controllability, and multilinguality. The speech docs show why that matters. You can prompt for delivery style directly, using instructions about tone, pace, accent, mood, and speaking behaviour.
Google also supports inline audio tags such as pauses, whispers, shouting, sighs, or emotional cues. For more advanced use, the docs recommend a fuller structure with an audio profile, scene, director’s notes, and the transcript itself. In practical terms, that means the model is not just a text reader. It is closer to a controllable voice performance layer.
3. Gemini 3.1 Flash TTS supports one or two speakers
Another important part of what is Gemini 3.1 Flash TTS is that it is not limited to one narrator. Google documents both single-speaker and multi-speaker generation, with support for up to two speakers in a single request.
That makes the model more useful for short interviews, dialogue clips, training role-play, support simulations, product walkthrough banter, or podcast-style excerpts. The important detail is that the speaker names in the prompt need to match the speaker configuration you pass in the API call.
4. Gemini 3.1 Flash TTS is multilingual and voice-selectable
Google documents 30 prebuilt voice options for Gemini TTS, with styles such as bright, upbeat, informative, firm, casual, smooth, lively, warm, and more. The docs also say the model automatically detects the input language and supports a wide range of languages, including English, Arabic, French, German, Hindi, Japanese, Korean, Mandarin, Portuguese, Spanish, Turkish, Urdu, Vietnamese, and many others.
That matters because multilingual support is only truly useful when paired with voice control. Gemini 3.1 Flash TTS is not just about translating a neutral voice across languages. It is about shaping the delivery in a way that fits the job.
5. Gemini 3.1 Flash TTS is a developer model with specific boundaries
What is Gemini 3.1 Flash TTS from an implementation standpoint? It is a preview API model with clear capabilities and clear exclusions. Google’s model page lists support for audio generation and Batch API, but not for Live API, caching, code execution, file search, function calling, structured outputs, search grounding, or URL context.
Google also lists an input token limit of 8,192 and an output token limit of 16,384 for the model. That is enough for many practical scripts, but it reinforces the idea that Gemini 3.1 Flash TTS is a specialised speech-generation model, not a general-purpose multimodal workhorse.
What Gemini 3.1 Flash TTS is good at
What is Gemini 3.1 Flash TTS best used for in practice? It is strongest when the script is known in advance and the delivery matters.
Scripted narration and voiceovers
Gemini 3.1 Flash TTS is a strong fit for product explainers, lessons, onboarding clips, article narration, training modules, video voiceovers, and spoken summaries. These workflows benefit from exact wording and controllable tone, which is where a dedicated TTS model has a real advantage.
Two-speaker dialogue and short conversational scenes
Because Google supports up to two speakers, the model is also useful for short podcast-style segments, role-play simulations, scenario-based training, and scripted back-and-forth content. That gives developers more flexibility than a single narrator workflow without forcing them into a real-time conversation stack.
Multilingual and localized content
Gemini 3.1 Flash TTS is also practical for teams that need speech output in multiple languages. The wide language coverage and voice selection make it a better fit for localization, regional product content, multilingual help flows, and cross-market training assets than a narrow English-only setup.
Prompt-shaped performance
One of the biggest reasons to care about Gemini 3.1 Flash TTS is the performance control. If you need a line spoken warmly, urgently, casually, dramatically, slowly, or with specific inline pauses and cues, Google’s prompting system gives you more direction than many basic TTS products expose by default.
How to access Gemini 3.1 Flash TTS today
What is Gemini 3.1 Flash TTS access like right now? It is available as a Preview model through the Gemini API and can also be explored in Google AI Studio.
Google’s code examples show the model name as gemini-3.1-flash-tts-preview. To use it, developers set the response modality to audio and pass a speech configuration that selects either a single prebuilt voice or a multi-speaker configuration. Google also provides a voice library in AI Studio so teams can preview voice styles before implementing them.
The practical onboarding path is straightforward:
- Write or generate the exact transcript you want spoken.
- Choose a single voice or configure two speakers.
- Add style directions, audio tags, or fuller director-style prompting if needed.
- Generate the audio through the Gemini API.
- Save the audio output and review it in the real production context.
For longer or more important workflows, Google recommends engineering discipline around the model. That includes using explicit prompting, splitting longer transcripts into smaller chunks, and adding automated retry behaviour where needed.
What Gemini 3.1 Flash TTS is still limited by
What is Gemini 3.1 Flash TTS not perfect at? Google’s own documentation is fairly direct about the tradeoffs.
- Gemini 3.1 Flash TTS is still in Preview, so behaviour, limits, and best practices may evolve.
- TTS models only take text input and return audio output, which means they are not replacements for multimodal conversational systems.
- Google explicitly says TTS does not support streaming.
- Google warns that speech quality and consistency may begin to drift for outputs longer than a few minutes, so longer scripts should be chunked.
- The docs note that the model can occasionally return text tokens instead of audio tokens, which can cause a
500error and should be handled with retries. - Google also warns that vague prompts can be misclassified or may lead the model to read style instructions aloud, so prompts should clearly separate direction from spoken transcript.
- If the chosen voice and the written prompt do not fit each other naturally, the resulting audio may sound mismatched.
These are not unusual limitations for a preview speech model, but they do matter. The cleanest way to think about Gemini 3.1 Flash TTS is as a promising production tool that still benefits from testing, chunking, and operational safeguards.
Frequently asked questions
Is Gemini 3.1 Flash TTS the same as the Live API?
No. Gemini 3.1 Flash TTS is a dedicated text-to-speech model for scripted audio generation. Google’s Live API is designed for interactive, real-time audio experiences.
Can Gemini 3.1 Flash TTS generate dialogue between two speakers?
Yes. Google documents support for multi-speaker generation with up to two configured speakers in a single request.
Can you control tone, pacing, and style?
Yes. Google supports natural-language prompting, audio tags, and more detailed direction structures for shaping how the speech is delivered.
Does Gemini 3.1 Flash TTS support streaming output?
No. Google’s speech-generation docs explicitly say TTS does not support streaming.
Is Gemini 3.1 Flash TTS good for long-form audio?
It can be used for longer scripts, but Google’s docs warn that quality may drift on outputs longer than a few minutes. In practice, chunking is the safer production approach.
Final thoughts
If you came here asking what is Gemini 3.1 Flash TTS, the most useful answer is that it is Google’s new preview speech model for turning scripts into more natural, more controllable audio. It matters because Google is not only offering text-to-speech output. It is offering a more directed performance layer with multilingual support, two-speaker generation, and prompt-based control that makes the result more usable in real workflows.
Whether Gemini 3.1 Flash TTS becomes a default choice for production speech generation will depend on how well Google moves it from Preview into stable deployment patterns. But right now, it already looks important for developers and teams that need exact text recitation with better control over how the audio actually sounds.
