Speech

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

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web

Installation

Terminal

→ npx expo install expo-speech

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

Usage

Speech

import * as React from 'react';
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>
  );
}

%%placeholder-start%%const styles = StyleSheet.create({ ... }); %%placeholder-end%%const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    backgroundColor: '#ecf0f1',
    padding: 8,
  },
});

API

import * as Speech from 'expo-speech';

Constants

`Speech.maxSpeechInputLength`

Type: number

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

Methods

`Speech.getAvailableVoicesAsync()`

Returns list of all available voices.

Returns

Promise<Voice[]>

List of Voice objects.

`Speech.isSpeakingAsync()`

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

Returns

Promise<boolean>

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

`Speech.pause()`

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

Returns

Promise<void>

`Speech.resume()`

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

Returns

Promise<void>

`Speech.speak(text, options)`

Name	Type	Description
text	`string`	The text to be spoken. Cannot be longer than `Speech.maxSpeechInputLength`.
options (optional)	`SpeechOptions`	A `SpeechOptions` object. 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()`

Interrupts current speech and deletes all in queue.

Returns

Promise<void>

Types

`SpeechEventCallback()`

Name	Type	Description
this	`SpeechSynthesisUtterance`	-
ev	`SpeechSynthesisEvent`	-

`SpeechOptions`

Name	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)	`SpeechEventCallback \| null`	-
onMark (optional)	`SpeechEventCallback \| null`	-
onPause (optional)	`SpeechEventCallback \| null`	-
onResume (optional)	`SpeechEventCallback \| null`	-
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.
voice (optional)	`string`	Voice identifier.
volume (optional)	`number`	Only for: Web Volume of the voice to speak `text`. A number between `0.0` (muted) and `1.0` (max volume) Default: `1.0`
onDone (optional)	`() => void`	A callback that is invoked when speaking finishes.
onError (optional)	`(error: Error) => void`	Only for: Android A callback that is invoked when an error occurred while speaking.
onStart (optional)	`() => void`	A callback that is invoked when speaking starts.
onStopped (optional)	`() => void`	A callback that is invoked when speaking is stopped by calling `Speech.stop()`.

`Voice`

Object describing the available voices on the device.

Name	Type	Description
identifier	`string`	Voice unique identifier.
language	`string`	Voice language.
name	`string`	Voice name.
quality	`VoiceQuality`	Voice quality.

`WebVoice`

Voice extended by:

Name	Type	Description
isDefault	`boolean`	-
localService	`boolean`	-
name	`string`	-
voiceURI	`string`	-

Speech

Platform Compatibility

Installation

Usage

API

Constants

`Speech.maxSpeechInputLength`

Methods

`Speech.getAvailableVoicesAsync()`

Returns

`Speech.isSpeakingAsync()`

Returns

`Speech.pause()`

Returns

`Speech.resume()`

Returns

`Speech.speak(text, options)`

Returns

`Speech.stop()`

Returns

Types

`SpeechEventCallback()`

`SpeechOptions`

`Voice`

`WebVoice`

Enums

`VoiceQuality`

`Default`

`Enhanced`