Source: https://docs.expo.dev/versions/latest/sdk/speech

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Expo Speech

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A library that provides access to text-to-speech functionality.

GitHub Changelog npm

Ask AI

Android

iOS

Web

Bundled version:

~14.0.7

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expo-speech provides an API that allows you to utilize Text-to-speech functionality in your app.

On iOS physical devices, expo-speech won't produce sound if the device is in silent mode. Make sure silent mode is turned off.

Installation

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Terminal

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- npx expo install expo-speech

If you are installing this in an existing React Native app , make sure to install expo in your project.

Usage

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Speech

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Open in Snack

import { View, StyleSheet, Button } from 'react-native'; import * as Speech from 'expo-speech'; export default function App() { const speak = () => { const thingToSay = '1'; Speech.speak(thingToSay); }; return ( <View style={styles.container}> <Button title="Press to hear some words" onPress={speak} /> </View> ); } const styles = StyleSheet.create({ container: { flex: 1, justifyContent: 'center', backgroundColor: '#ecf0f1', padding: 8, }, });

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API

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import * as Speech from 'expo-speech';

Constants

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Speech.maxSpeechInputLength

Android

iOS

Web

Type: number

Maximum possible text length acceptable by Speech.speak() method. It is platform-dependent. On iOS, this returns Number.MAX_VALUE.

Methods

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Speech.getAvailableVoicesAsync()

Android

iOS

Web

Returns list of all available voices.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <[Voice[]](https://docs.expo.dev/versions/latest/sdk/speech#voice) >

List of Voice objects.

Speech.isSpeakingAsync()

Android

iOS

Web

Determine whether the Text-to-speech utility is currently speaking. Will return true if speaker is paused.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <boolean>

Returns a Promise that fulfils with a boolean, true if speaking, false if not.

Speech.pause()

Android

iOS

Web

Pauses current speech. This method is not available on Android.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <void>

Speech.resume()

Android

iOS

Web

Resumes speaking previously paused speech or does nothing if there's none. This method is not available on Android.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <void>

Speech.speak(text, options)

Android

iOS

Web

| Parameter | Type | Description | | --- | --- | --- | | text | string | The text to be spoken. Cannot be longer than Speech.maxSpeechInputLength<br>. | | options(optional) | [SpeechOptions](https://docs.expo.dev/versions/latest/sdk/speech#speechoptions) | A SpeechOptions object.<br><br>Default:{} |

Speak out loud the text given options. Calling this when another text is being spoken adds an utterance to queue.

Returns:

void

Speech.stop()

Android

iOS

Web

Interrupts current speech and deletes all in queue.

Returns:

[Promise](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise) <void>

Types

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SpeechEventCallback(this, ev)

Android

iOS

Web

| Parameter | Type | | --- | --- | | this | [SpeechSynthesisUtterance](https://developer.mozilla.org/en-US/docs/Web/API/SpeechSynthesisUtterance) | | ev | [SpeechSynthesisEvent](https://developer.mozilla.org/en-US/docs/Web/API/SpeechSynthesisEvent) |

Returns:

any

SpeechOptions

Android

iOS

Web

| Property | Type | Description | | --- | --- | --- | | _voiceIndex(optional) | number | - | | language(optional) | string | The code of a language that should be used to read the text, refer to IETF BCP 47 to see valid codes. | | onBoundary(optional) | NativeBoundaryEventCallback \| [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) \| null | A callback that is invoked when the spoken utterance reaches a word. | | onDone(optional) | () => void \| [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) | A callback that is invoked when speaking finishes. | | onError(optional) | (error: [Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error) ) => void \| [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) | Only for: <br><br>Android<br><br>iOS<br><br> <br><br>A callback that is invoked when an error occurred while speaking. | | onMark(optional) | [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) \| null | - | | onPause(optional) | [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) \| null | - | | onResume(optional) | [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) \| null | - | | onStart(optional) | () => void \| [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) | A callback that is invoked when speaking starts. | | onStopped(optional) | () => void \| [SpeechEventCallback](https://docs.expo.dev/versions/latest/sdk/speech#speecheventcallback) | A callback that is invoked when speaking is stopped by calling Speech.stop(). | | pitch(optional) | number | Pitch of the voice to speak text. 1.0 is the normal pitch. | | rate(optional) | number | Rate of the voice to speak text. 1.0 is the normal rate. | | useApplicationAudioSession(optional) | boolean | Only for: <br><br>iOS<br><br> <br><br>If you set this value to false, the system creates a separate audio session to automatically manage speech, interruptions, and mixing and ducking the speech with other audio sources. | | voice(optional) | string | Voice identifier. | | volume(optional) | number | Only for: <br><br>Web<br><br> <br><br>Volume of the voice to speak text. A number between 0.0 (muted) and 1.0 (max volume)<br><br>Default:1.0 |

Voice

Android

iOS

Web

Object describing the available voices on the device.

| Property | Type | Description | | --- | --- | --- | | identifier | string | Voice unique identifier. | | language | string | Voice language. | | name | string | Voice name. | | quality | [VoiceQuality](https://docs.expo.dev/versions/latest/sdk/speech#voicequality) | Voice quality. |

WebVoice

Android

iOS

Web

Type: [Voice](https://docs.expo.dev/versions/latest/sdk/speech#voice) extended by:

| Property | Type | Description | | --- | --- | --- | | isDefault | boolean | - | | localService | boolean | - | | name | string | - | | voiceURI | string | - |

Enums

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VoiceQuality

Android

iOS

Web

Enum representing the voice quality.

Default

VoiceQuality.Default ＝ "Default"

Enhanced

VoiceQuality.Enhanced ＝ "Enhanced"