Google Gemini 3.1 Flash Text To Speech API Documentation

Playground

Gemini 3.1 Flash Text to Speech generates expressive multi-speaker audio from text, with natural voices and multilingual language control for dialogue, narration, localization, and AI voice workflows. Ready-to-use REST inference API, best performance, no coldstarts, affordable pricing.

Features

Gemini 3.1 Flash Text-to-Speech turns scripts and labelled dialogue into expressive spoken audio. Assign a distinct voice to each speaker and generate one natural, multilingual audio track for narration, conversations, and voiceover workflows.

Why Choose This?

Expressive speech generation
Create natural pacing, tone, and delivery from written scripts.
Multi-speaker dialogue
Assign different voices to up to two named speakers in one generation.
Multilingual voice output
Select the language and locale that match the script for stronger pronunciation.
Voice preset control
Choose from a library of voice presets for narration, dialogue, announcements, and character reads.
Standard audio output
Generated audio is returned as a URL in the standard WaveSpeed prediction response.

Parameters

Parameter	Required	Description
text	Yes	Script or dialogue to synthesize. Use each speaker name exactly as configured in `speakers`.
language	Yes	Language and locale spoken in the generated audio.
speakers	No	Optional. Provide two or more speaker entries (each a speaker name plus a voice) to generate multi-speaker dialogue. Omit it for single-speaker synthesis.
voice	No	Voice preset when generating with a single speaker. Ignored if `speakers` is provided.

How to Use

Write your script — Use a consistent Speaker: dialogue format, such as Narrator: Welcome to the show.
Choose a language — Select the language and locale for the spoken audio.
Choose your voices — for a single narrator, pick a voice. For dialogue, add one speakers entry per speaker label used in the script.
Submit — Generate the spoken audio and retrieve the output URL.

Pricing

Pricing is $0.20 per 1,000 characters of input text, billed by actual character count with a $0.01 minimum per request.

Text Length	Price
50 characters	$0.01 (minimum)
250 characters	$0.05
1,000 characters	$0.20
2,000 characters	$0.40
5,000 characters	$1.00

Best Use Cases

Dialogue generation — Create conversations with different named voices.
Narration and voiceover — Produce spoken scripts for videos, presentations, and explainers.
Podcasts and audio stories — Generate host or character dialogue from structured scripts.
Multilingual content — Create localized speech with language-aware voice output.
Product demos — Turn scripted product messaging into polished audio.

Pro Tips

Make every speaker label in the script exactly match the corresponding speaker entry.
Keep punctuation clear to guide pauses, emphasis, and delivery.
Use one speaker for narration and two speakers for dialogue.
Match the selected language to the language used in the script.
Split long scripts into logical sections for more consistent pacing.


## Authentication

For authentication details, please refer to the [Authentication Guide](/api-authentication).

## API Endpoints

### Submit Task & Query Result

<ApiTabs submitUrl={model.submitUrl} resultUrl={model.resultUrl} payload={model.defaultValues} />

## Parameters

### Task Submission Parameters

#### Request Parameters

<RequestParams params={model.params} />

#### Response Parameters

<SubmitResponse />

#### Result Request Parameters

| Parameter | Type | Required | Default | Description |
|-----------|------|----------|---------|-------------|
| id | string | Yes | - | Task ID |

#### Result Response Parameters

| Parameter | Type | Description |
|-----------|------|-------------|
| code | integer | HTTP status code (e.g., 200 for success) |
| message | string | Status message (e.g., "success") |
| data | object | The prediction data object containing all details |
| data.id | string | Unique identifier for the prediction |
| data.model | string | Model ID used for the prediction |
| data.outputs | array&lt;string \| object&gt; | Array of generated outputs (empty when status is not completed). Items are usually URL strings, but may be text strings or structured result objects, depending on the model. |
| data.urls | object | Object containing related API endpoints |
| data.status | string | Status: `completed` is successful; `failed`, `cancelled`, `timeout`, and `deleted` are failure terminal statuses |
| data.created_at | string | ISO timestamp of when the request was created |
| data.error | string | Error message (empty if no error occurred) |
| data.timings | object | Object containing timing details |
| data.timings.inference | integer | Inference time in milliseconds |

Overview