🎙️ expo-speech-recognition

expo-speech-recognition implements the iOS SFSpeechRecognizer, Android SpeechRecognizer and Web SpeechRecognition for React Native projects with the goal of code reuse across web and mobile.

Installation
Usage
Speech Recognition Events
Handling Errors
Persisting Audio Recordings
Transcribing audio files
- Supported input audio formats
  - Android
  - iOS
- File transcription example
Polyfilling the Web SpeechRecognition API
Muting the beep sound on Android
Improving accuracy of single-word prompts
Platform Compatibility Table
API Methods

Installation

Install the package

npm install expo-speech-recognition

Configure the config plugin.

The config plugin updates the Android App Manifest to include package visibility filtering for com.google.android.googlequicksearchbox (Google's Speech Recognition) along with the required permissions for Android and iOS.

// app.json
{
  "expo": {
    "plugins": [
      [
        "expo-speech-recognition",
        {
          "microphonePermission": "Allow $(PRODUCT_NAME) to use the microphone.",
          "speechRecognitionPermission": "Allow $(PRODUCT_NAME) to use speech recognition.",
          // Add additional speech service packages here that aren't listed
          // under the `forceQueryable` section when running the command:
          // "adb shell dumpsys package queries"
          // default: ["com.google.android.googlequicksearchbox"]
          "androidSpeechServicePackages": ["com.google.android.googlequicksearchbox"]
        }
      ]
    ]
  }
}

Important Note for Expo Beginners (click to expand)

Important Note for Expo Beginners

If you've just created a new Expo project or have only been using the Expo SDK so far (without ios/ and android/ directories), you'll need to create a development build. Don't worry—this won't drastically change your workflow. For a better understanding of the differences between the React Native and Expo folder structures, check out this video at the relevant timestamp.

After completing Step 2: Configure the config plugin, follow these steps:

To (re)-generate the native Android project, run:
```
npx expo run:android
```
To (re)-generate the native iOS project, run:
```
npx expo run:ios
```

For more details, see Expo's prebuild documentation.

Best Practices for Version Control

It's recommended by the Expo team to add the ios/ and android/ directories to your .gitignore file and rely on Continuous Native Generation. This approach has its own benefits, as outlined in the Expo documentation.

Now, you're ready to move on to the Usage section.

Usage

Using Hooks

Using hooks is the easiest way to get started. The useSpeechRecognitionEvent hook allows you to register native event listeners.

import {
  ExpoSpeechRecognitionModule,
  useSpeechRecognitionEvent,
} from "expo-speech-recognition";

function App() {
  const [recognizing, setRecognizing] = useState(false);
  const [transcript, setTranscript] = useState("");

  useSpeechRecognitionEvent("start", () => setRecognizing(true));
  useSpeechRecognitionEvent("end", () => setRecognizing(false));
  useSpeechRecognitionEvent("result", (event) => {
    setTranscript(event.results[0]?.transcript);
  });
  useSpeechRecognitionEvent("error", (event) => {
    console.log("error code:", event.error, "error messsage:", event.message);
  });

  const handleStart = async () => {
    const result = await ExpoSpeechRecognitionModule.requestPermissionsAsync();
    if (!result.granted) {
      console.warn("Permissions not granted", result);
      return;
    }
    // Start speech recognition
    ExpoSpeechRecognitionModule.start({
      lang: "en-US",
      interimResults: true,
      maxAlternatives: 1,
      continuous: false,
      requiresOnDeviceRecognition: false,
      addsPunctuation: false,
      contextualStrings: ["Carlsen", "Nepomniachtchi", "Praggnanandhaa"],
    });
  };

  return (
    <View>
      {!recognizing ? (
        <Button title="Start" onPress={handleStart} />
      ) : (
        <Button title="Stop" onPress={ExpoSpeechRecognitionModule.stop} />
      )}

      <ScrollView>
        <Text>{transcript}</Text>
      </ScrollView>
    </View>
  );
}

Permissions

You should request permissions prior to starting recognition. This library exports two functions: getPermissionsAsync and requestPermissionsAsync for this purpose. If you do not request permissions or the user has denied permissions after starting, expect an error event with the error code set to not-allowed.

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

ExpoSpeechRecognitionModule.getPermissionsAsync().then((result) => {
  console.log("Status:", result.status);
  console.log("Granted:", result.granted);
  console.log("Can ask again:", result.canAskAgain);
  console.log("Expires:", result.expires);
});

ExpoSpeechRecognitionModule.requestPermissionsAsync().then((result) => {
  if (!result.granted) {
    console.warn("Permissions not granted", result);
    return;
  }
  // Permissions granted! Start speech recognition, or at some other time...
  ExpoSpeechRecognitionModule.start({ lang: "en-US" });
});

Direct module API

You can also use the ExpoSpeechRecognitionModule to use the native APIs directly. The listener events are similar to the Web Speech API.

import {
  ExpoSpeechRecognitionModule,
  addSpeechRecognitionListener,
} from "expo-speech-recognition";

// Register event listeners
const startListener = addSpeechRecognitionListener("start", () => {
  console.log("Speech recognition started");
});

// and remove the listener when you're done:
startListener.remove();

const endListener = addSpeechRecognitionListener("end", () => {
  console.log("Speech recognition ended");
});

const resultListener = addSpeechRecognitionListener("result", (event) => {
  // Note: this is not the same as the `result` event listener on the web speech API
  // event.results is an array of results (e.g. `[{ transcript: "hello", confidence: 0.5, segments: [] }]`)
  console.log("results:", event.results, "final:", event.isFinal);
});

const errorListener = addSpeechRecognitionListener("error", (event) => {
  console.log("error code:", event.error, "error messsage:", event.message);
});

// Start speech recognition
ExpoSpeechRecognitionModule.start({
  lang: "en-US",
  // Whether to return results as they become available without waiting for the final result.
  interimResults: true,
  // The maximum number of alternative transcriptions to return.
  maxAlternatives: 1,
  // Continuous recognition. Note: if false on iOS, recognition will run until no speech is detected for 3 seconds
  continuous: true,
  // [Default: false] Prevent device from sending audio over the network. Only enabled if the device supports it.
  requiresOnDeviceRecognition: false,
  // [Default: false] Include punctuation in the recognition results. This applies to full stops and commas.
  addsPunctuation: false,
  // [Default: undefined] Short custom phrases that are unique to your app.
  contextualStrings: ["Carlsen", "Nepomniachtchi", "Praggnanandhaa"],
  // [Default: undefined] Android-specific options to pass to the recognizer.
  androidIntentOptions: {
    EXTRA_SPEECH_INPUT_COMPLETE_SILENCE_LENGTH_MILLIS: 10000,
    EXTRA_MASK_OFFENSIVE_WORDS: false,
  },
  // [Default: undefined] The package name of the speech recognition service to use.
  androidRecognitionServicePackage: "com.google.android.tts",
  // [Default: unspecified] The type of speech recognition being performed.
  iosTaskHint: "unspecified", // "unspecified" | "dictation" | "search" | "confirmation"
  // [Default: undefined] The audio session category and options to use.
  iosCategory: {
    category: "playAndRecord",
    categoryOptions: ["defaultToSpeaker", "allowBluetooth"],
    mode: "measurement",
  },
  // [Default: undefined] Recording options for Android & iOS
  // For Android, this is only supported on Android 13 and above.
  recordingOptions: {
    // [Default: false] Whether to persist the audio to a local file path.
    persist: false,
    // [Default: FileSystem.CacheDirectory]
    // Changes the default storage location for the audio file.
    // e.g. `FileSystem.documentDirectory` (from `expo-file-system`)
    outputDirectory: undefined,
    // [Default: `"recording_${timestamp|uuid}.[wav|caf]"`]
    // Changes the file name for the audio file.
    // (you can retrieve the file path using `event.uri` on the `audiostart`/`audioend` events)
    outputFileName: "recording.wav",
    // [Default: undefined] The sample rate of the output audio file.
    // Only supported on iOS
    // Default sample rate is: 16000 on Android, 44100/48000 on iOS
    outputSampleRate: undefined,
    // [Default: undefined] The encoding of the output audio file.
    // Only supported on iOS
    outputEncoding: undefined,
  },
  // [Default: undefined] Use for file-based transcription.
  audioSource: {
    /** Local file URI, e.g. "file:///path/to/audio.wav" */
    uri: undefined,
    // [Android only] The number of channels in the source audio.
    audioChannels: 1,
    // [Android only] A value from AudioFormat - https://developer.android.com/reference/android/media/AudioFormat
    audioEncoding: AudioEncodingAndroid.ENCODING_PCM_16BIT,
    // [Android only] Audio sampling rate in Hz.
    sampleRate: 16000,
    // [Android only] The delay between chunks of audio to stream to the speech recognition service.
    // Use this setting to avoid being rate-limited when using network-based recognition.
    // Default: 50ms for network-based recognition, 15ms for on-device recognition
    chunkDelayMillis: undefined,
  },
});

// Stop capturing audio (and emit a final result if there is one)
ExpoSpeechRecognitionModule.stop();

// Immediately cancel speech recognition (does not process the final result)
ExpoSpeechRecognitionModule.abort();

Speech Recognition Events

Events are largely based on the Web Speech API. The following events are supported:

Event Name	Description	Notes
`audiostart`	Audio capturing has started	Includes the `uri` if `recordingOptions.persist` is enabled.
`audioend`	Audio capturing has ended	Includes the `uri` if `recordingOptions.persist` is enabled.
`end`	Speech recognition service has disconnected.	This should be the last event dispatched.
`error`	Fired when a speech recognition error occurs.	You'll also receive an `error` event (with code "aborted") when calling `.abort()`
`nomatch`	Speech recognition service returns a final result with no significant recognition.	You may have non-final results recognized. This may get emitted after cancellation.
`result`	Speech recognition service returns a word or phrase has been positively recognized.	On Android, continous mode runs as a segmented session, meaning when a final result is reached, additional partial and final results will cover a new segment separate from the previous final result. On iOS, you should expect one final result before speech recognition has stopped.
`speechstart`	Fired when any sound — recognizable speech or not — has been detected	On iOS, this will fire once in the session after a result has occurred
`speechend`	Fired when speech recognized by the speech recognition service has stopped being detected.	Not supported yet on iOS
`start`	Speech recognition has started	Use this event to indicate to the user when to speak.

Handling Errors

To handle errors, you can listen to the error event:

import {
  type ExpoSpeechRecognitionErrorCode,
  addSpeechRecognitionListener,
  useSpeechRecognitionEvent,
} from "expo-speech-recognition";

addSpeechRecognitionListener("error", (event) => {
  console.log("error code:", event.error, "error messsage:", event.message);
});

// or through the `useSpeechRecognitionEvent` hook
useSpeechRecognitionEvent("error", (event) => {
  console.log("error code:", event.error, "error messsage:", event.message);
});

// or through the `ExpoSpeechRecognitionErrorCode` type
const error: ExpoSpeechRecognitionErrorCode = "audio-capture";

The error code is largely based on the Web Speech API error codes.

Error Code	Description
`aborted`	The user called `ExpoSpeechRecognitionModule.abort()`
`audio-capture`	Audio recording error.
`bad-grammar`	Provided grammar is invalid. (Note: web only)
`language-not-supported`	Locale is not supported by the speech recognizer.
`network`	Network communication required for completing the recognition failed.
`no-speech`	No final speech was detected.
`not-allowed`	Permission to use speech recognition or microphone was not granted.
`service-not-allowed`	Recognizer is unavailable.
`busy`	The recognizer is busy and cannot accept any new recognition requests.
`client`	(Android) Unknown error. Corresponds with `SpeechRecognizer.ERROR_CLIENT`.

Persisting Audio Recordings

If you would like to persist the recognized audio for later use, you can enable the recordingOptions.persist option when calling start(). Enabling this setting will emit an { uri: string } event object in the audiostart and audioend events with the local file path.

Important

For Android, this is only supported on Android 13 and above. Call supportsRecording() to see if it's available before using this feature.

Default audio output formats:

Platform	Output Format	Notes
Android	Linear PCM (16000 Hz, mono)	Suitable for processing on various external services (such as Google Speech API, Whisper, Deepgram, etc)
iOS	32-bit Float PCM (44100/48000* Hz, mono)	Default sample rate is device specific. Change this with `recordingOptions.outputSampleRate` and `recordingOptions.outputEncoding`.

Example:

import { Button, View } from "react-native";
import {
  ExpoSpeechRecognitionModule,
  useSpeechRecognitionEvent,
} from "expo-speech-recognition";

function RecordAudio() {
  const [recording, setRecording] = useState(false);
  const [recordingUri, setRecordingUri] = useState<string | null>(null);

  const handleStart = () => {
    setRecording(true);
    // Start recording
    ExpoSpeechRecognitionModule.start({
      lang: "en-US",
      recordingOptions: {
        persist: true,
        // Optional: Specify the output file path to save the recording to
        // e.g. `FileSystem.documentDirectory` (from `expo-file-system`)
        outputDirectory:
          "/data/user/0/expo.modules.speechrecognition.example/files",
        // Optional: Specify the output file name to save the recording to
        outputFileName: "recording.wav",
        // Optional: Specify the output sample rate to save the recording to
        // Only supported on iOS
        // Default sample rate: 16000 on Android, 44100/48000 on iOS
        outputSampleRate: 16000,
        // Optional: Specify the output encoding to save the recording to
        // Only supported on iOS
        // Default encoding: pcmFormatInt16 on Android, pcmFormatFloat32 on iOS
        outputEncoding: "pcmFormatInt16",
      },
    });
  };

  useSpeechRecognitionEvent("audiostart", (event) => {
    // Note: don't use this file until the "audioend" event is emitted
    // Note: event.uri will be null if `recordingOptions.persist` is not enabled
    console.log("Recording started for file:", event.uri);
  });

  useSpeechRecognitionEvent("audioend", (event) => {
    // Recording ended, the file is now safe to use
    console.log("Local file path:", event.uri);
    // Android: Will be saved as a .wav file
    // e.g. "file:///data/user/0/expo.modules.speechrecognition.example/cache/recording_1720678500903.wav"
    // iOS: Will be saved as a .caf file
    // e.g. "file:///path/to/Library/Caches/audio_CD5E6C6C-3D9D-4754-9188-D6FAF97D9DF2.caf"
    setRecordingPath(event.uri);
  });

  return (
    <View>
      <Button title="Start" onPress={handleStart} disabled={recording} />
      {recordingUri && <AudioPlayer source={recordingUri} />}
    </View>
  );
}

// AudioPlayer.tsx
import { Button } from "react-native";
import { useAudioPlayer } from "expo-audio";

function AudioPlayer(props: { source: string }) {
  const player = useAudioPlayer(props.source);
  return <Button title="Play" onPress={player.play} />;
}

Transcribing audio files

You can use the audioSource.uri option to transcribe audio files instead of using the microphone.

Important

This feature is available on Android 13+ and iOS. If the device does not support the feature, you'll receive an error event with the code audio-capture.

Supported input audio formats

Android

The following audio formats have been verified on a Samsung Galaxy S23 Ultra on Android 14:

16000hz 16-bit 1-channel PCM WAV (example file)
16000hz MP3 1-channel (example file)
16000hz MP3 2-channel
16000hz ogg vorbis 1-channel (example file)

iOS

Due to a limitation in the underlying SFSpeechURLRecognitionRequest API, file-based transcription will only transcribe the first 1 minute of the audio file.

The following audio formats have been verified on an iPhone 15 Pro Max on iOS 17.5:

16000hz 16-bit 1-channel PCM WAV (example file)
16000hz MP3 1-channel (example file)

File transcription example

import { Button, View } from "react-native";
import {
  ExpoSpeechRecognitionModule,
  useSpeechRecognitionEvent,
  AudioEncodingAndroid,
} from "expo-speech-recognition";

function TranscribeAudioFile() {
  const [transcription, setTranscription] = useState("");

  const handleTranscribe = () => {
    ExpoSpeechRecognitionModule.start({
      lang: "en-US",
      interimResults: true,
      audioSource: {
        /** Local file URI */
        uri: "file:///path/to/audio.wav",
        /** [Android only] The number of channels in the source audio. */
        audioChannels: 1,
        /** [Android only] A value from AudioFormat - https://developer.android.com/reference/android/media/AudioFormat */
        audioEncoding: AudioEncodingAndroid.ENCODING_PCM_16BIT,
        /** [Android only] Audio sampling rate in Hz. */
        sampleRate: 16000,
        /**
         * [Android only] The delay between chunks of audio to stream to the speech recognition service.
         * Use this setting to avoid being rate-limited when using network-based recognition.
         * If you're using on-device recognition, you may want to increase this value to avoid unprocessed audio chunks.
         * Default: 50ms for network-based recognition, 15ms for on-device recognition
         */
        chunkDelayMillis: undefined,
      },
    });
  };

  useSpeechRecognitionEvent("result", (ev) => {
    // Note: multiple final results will likely be returned on Android
    // so you'll need to concatenate previous final results
    setTranscription(ev.results[0]?.transcript || "");
  });

  return (
    <View>
      <Button title="Transcribe" onPress={handleTranscribe} />
      <Text>{transcription}</Text>
    </View>
  );
}

Polyfilling the Web SpeechRecognition API

Important

This is intended for projects that rely on third party libraries that use the Web Speech API. If you're using this library directly, you should use the Direct Module API instead.

If you intend to polyfill the webkitSpeechRecognition or SpeechRecognition globals for use with external libraries, you can use the ExpoWebSpeechRecognition class to do so.

Refer to the SpeechRecognition MDN docs for usage. Note that some features (such as grammars) on some OSes aren't yet supported.

// Import this polyfill for typings, as needed
// "npm install -D @types/dom-speech-recognition"
import "dom-speech-recognition";

import { ExpoWebSpeechRecognition } from "expo-speech-recognition";

// Polyfill the globals for use in external libraries
webkitSpeechRecognition = ExpoWebSpeechRecognition;
SpeechRecognition = ExpoWebSpeechRecognition;

// Usage is the same as the Web Speech API..
const recognition = new ExpoWebSpeechRecognition();

recognition.lang = "en-US";
// [Default: false] Note for iOS: final results are only available after speech recognition has stopped
recognition.interimResults = true;
recognition.maxAlternatives = 1;
// [Default: false] Continuous recognition. Note: if false on iOS, recognition will run until no speech is detected for 3 seconds
recognition.continuous = true;

// Custom (non-web) properties

recognition.contextualStrings = ["Carlsen", "Nepomniachtchi", "Praggnanandhaa"];
recognition.requiresOnDeviceRecognition = true;
recognition.addsPunctuation = true;
recognition.androidIntentOptions = {
  EXTRA_LANGUAGE_MODEL: "web_search",
};
recognition.androidRecognitionServicePackage = "com.google.android.tts";

// Assign an event listener (note: this overwrites all event listeners)
recognition.onstart = (event) => console.log("started!");
recognition.onend = (event) => console.log("ended!");
recognition.onresult = (event) => {
  console.log(
    "result:",
    event.results[event.resultIndex][0].transcript,
    "final:",
    event.results[event.resultIndex][0].isFinal,
  );
};

// Or register an event listener
const handleStart = (event: Event) => console.log("started!");
recognition.registerEventListener("start", handleStart);
// and remember to unregister after you're done:
recognition.unregisterEventListener("start", handleStart);

const handleResult = (event: SpeechRecognitionEvent) => {
  console.log("result:", event.results[event.resultIndex][0].transcript);
};

recognition.registerEventListener("result", handleResult);

recognition.registerEventListener("error", (event) => {
  console.log("error code:", event.error, "error messsage:", event.message);
});

recognition.registerEventListener("end", (event) => console.log("ended!"));

// Start speech recognition
recognition.start();

// Stop speech recognition
recognition.stop();

// Immediately cancel speech recognition
recognition.abort();

Muting the beep sound on Android

On Android, you may notice that there's a beep sound when you start and stop speech recognition. This is due to a hardcoded behavior in the underlying SpeechRecognizer API. However, a workaround you can use is by enabling continuous recognition:

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

ExpoSpeechRecognitionModule.start({
  lang: "en-US",
  continuous: true,
});

Under the hood, this sets the EXTRA_AUDIO_SOURCE in the recognizer intent to a custom microphone source instead of using the default microphone setting.

To maintain the same behavior as non-continuous mode, you should listen for a result event with isFinal: true and then immediately call abort() to stop the recognition.

Improving accuracy of single-word prompts

You may notice that after saying short syllables, words, letters, or numbers (e.g. "a", "b", 1, 5, etc.) that the speech recognition service may not return any results until you speak further. In order to improve the accuracy of single-word prompts for Android and iOS, you have the following options:

For iOS, you can use the iosTaskHint option and set it to confirmation.
For Android, the Google Development team recommends to use the web_search language model for this specific issue. You can change to that model (from the default free_form) by adding androidIntentOptions: { EXTRA_LANGUAGE_MODEL: "web_search" } to ExpoSpeechRecognitionModule.start(...).
For both platforms, you also may want to consider using on-device recognition. On Android this seems to work well for single-word prompts.
Alternatively, you may want to consider recording the recognized audio and sending it to an external service for further processing. See Persisting Audio Recordings for more information. Note that some services (such as the Google Speech API) may require an audio file with a duration of at least 3 seconds.

Platform Compatibility Table

As of 7 Aug 2024, the following platforms are supported:

Platform	Supported	Default Recognition Engine	Notes
Android (React Native)	✅	Google	Recording feature is only supported on Android 13 and above. Recognition engine can be changed via `androidRecognitionServicePackage`
iOS (React Native)	✅	Siri
Chrome Desktop	✅	Google (server-based)	Implemented via prefix `webkitSpeechRecognition`.
Safari Desktop >= v16	✅	Siri	Implemented via prefix `webkitSpeechRecognition`. Siri needs to be enabled
Chrome on Android	✅	Google	There's a few differences in how results get handled in comparison to the Chrome Desktop implementation
Chrome on iOS	❌	Google	Not working (Last tested 2023)
Edge on Windows	(unknown)	Azure	SpeechRecognition API is implemented, but requires the Azure speech component. Verify it’s presence at `edge://components`
Edge on Mac ARM	❌	Azure	SpeechRecognition API is implemented, but requires the Azure speech component. Verify it’s presence at `edge://components`
Brave Desktop	❌	-	As of Aug 2024, Brave is working on an implementation however there's currently no ETA (source: brave-browser/issues/3725)
Firefox Desktop	❌	-	No SpeechRecognition implementation

API Methods

`start(options: SpeechRecognitionOptions): void`

Starts speech recognition.

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

ExpoSpeechRecognitionModule.start({
  lang: "en-US",
});

`stop(): void`

Stops speech recognition and attempts to return a final result (through the result event).

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

ExpoSpeechRecognitionModule.stop();
// Expect the following events to be emitted in order:
// One of:
//       - A "result" event containing the final result,
//       - A "nomatch" event if the final result was empty
//      -  A "error" event with the code "no-speech" if no speech was detected
// - "audioend" indicating the end of recording
// - "end" indicating the end of speech recognition

`abort(): void`

Immediately cancels speech recognition (does not process the final result).

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

ExpoSpeechRecognitionModule.abort();
// Expect an "error" event to be emitted with the code "aborted"

`requestPermissionsAsync(): Promise<PermissionResponse>`

Presents a dialog to the user to request permissions for using speech recognition and the microphone.

For iOS, once a user has granted (or denied) location permissions by responding to the original permission request dialog, the only way that the permissions can be changed is by the user themselves using the device settings app.

import { requestPermissionsAsync } from "expo-speech-recognition";

requestPermissionsAsync().then((result) => {
  console.log("Status:", result.status); // "granted" | "denied" | "not-determined"
  console.log("Granted:", result.granted); // true | false
  console.log("Can ask again:", result.canAskAgain); // true | false
  console.log("Expires:", result.expires); // "never" | number
});

`getPermissionsAsync(): Promise<PermissionResponse>`

Returns the current permission status for the microphone and speech recognition.

import { getPermissionsAsync } from "expo-speech-recognition";

getPermissionsAsync().then((result) => {
  console.log("Status:", result.status); // "granted" | "denied" | "not-determined"
  console.log("Granted:", result.granted); // true | false
  console.log("Can ask again:", result.canAskAgain); // true | false
  console.log("Expires:", result.expires); // "never" | number
});

`getStateAsync(): Promise<SpeechRecognitionState>`

Returns the current internal state of the speech recognizer.

import { getStateAsync } from "expo-speech-recognition";

// Note: you probably should rather rely on the events emitted by the SpeechRecognition API instead
getStateAsync().then((state) => {
  console.log("Current state:", state);
  // "inactive" | "starting" | "stopping" | "recognizing"
});

`addSpeechRecognitionListener(eventName: string, listener: (event: any) => void): { remove: () => void }`

import { addSpeechRecognitionListener } from "expo-speech-recognition";

const listener = addSpeechRecognitionListener("result", (event) => {
  console.log("result:", event.results[event.resultIndex][0].transcript);
});

// Remove the listener when you're done
listener.remove();

`getSupportedLocales(): Promise<{ locales: string[]; installedLocales: string[] }>`

Note

Not supported on Android 12 and below

Get the list of supported locales and the installed locales that can be used for on-device speech recognition.

import { getSupportedLocales } from "expo-speech-recognition";

getSupportedLocales({
  /**
   * The package name of the speech recognition service to use.
   * If not provided, the default service used for on-device recognition will be used.
   *
   * Warning: the service package (such as Bixby) may not be able to return any results.
   */
  androidRecognitionServicePackage: "com.google.android.as",
})
  .then((supportedLocales) => {
    console.log("Supported locales:", supportedLocales.locales.join(", "));

    // The on-device locales for the provided service package.
    // Likely will be empty if it's not "com.google.android.as"
    console.log(
      "On-device locales:",
      supportedLocales.installedLocales.join(", "),
    );
  })
  .catch((error) => {
    // If the service package is not found
    // or there was an error retrieving the supported locales
    console.error("Error getting supported locales:", error);
  });

`getSpeechRecognitionServices(): string[]` (Android only)

Get list of speech recognition services available on the device.

Note

This only includes services that are listed under androidSpeechServicePackages in your app.json as well as the core services listed under forceQueryable when running the command: adb shell dumpsys package queries

import { getSpeechRecognitionServices } from "expo-speech-recognition";

const packages = ExpoSpeechRecognitionModule.getSpeechRecognitionServices();
console.log("Speech recognition services:", packages.join(", "));
// e.g. ["com.google.android.as", "com.google.android.tts", "com.samsung.android.bixby.agent"]

`getDefaultRecognitionService(): { packageName: string }` (Android only)

Returns the default voice recognition service on the device.

import { getDefaultRecognitionService } from "expo-speech-recognition";

const service = ExpoSpeechRecognitionModule.getDefaultRecognitionService();
console.log("Default recognition service:", service.packageName);
// Usually this is "com.google.android.tts", however "com.google.android.as" will likely be used for on-device recognition.

`getAssistantService(): { packageName: string }` (Android only)

Returns the default voice assistant service on the device.

import { getAssistantService } from "expo-speech-recognition";

const service = ExpoSpeechRecognitionModule.getAssistantService();
console.log("Default assistant service:", service.packageName);
// Usually "com.google.android.googlequicksearchbox" for Google
// or "com.samsung.android.bixby.agent" for Samsung

`supportsOnDeviceRecognition(): boolean`

Whether on-device speech recognition is available on the device.

import { supportsOnDeviceRecognition } from "expo-speech-recognition";

const available = supportsOnDeviceRecognition();
console.log("OnDevice recognition available:", available);

`supportsRecording(): boolean` (Android only)

Whether audio recording is supported during speech recognition. This mostly applies to Android devices, to check if it's at least Android 13.

import { supportsRecording } from "expo-speech-recognition";

const available = supportsRecording();
console.log("Recording available:", available);

`androidTriggerOfflineModelDownload({ locale: string }): Promise<{ status: "opened_dialog" | "download_success" | "download_canceled", message: string }>`

Users on Android devices will first need to download the offline model for the locale they want to use in order to use on-device speech recognition (i.e. the requiresOnDeviceRecognition setting in the start options).

You can see which locales are supported and installed on your device by running getSupportedLocales().

To download the offline model for a specific locale, use the androidTriggerOfflineModelDownload function.

import { ExpoSpeechRecognitionModule } from "expo-speech-recognition";

// Download the offline model for the specified locale
ExpoSpeechRecognitionModule.androidTriggerOfflineModelDownload({
  locale: "en-US",
})
  .then((result) => {
    switch (result.status) {
      case "opened_dialog":
        // On Android 13, the status will be "opened_dialog" indicating that the model download dialog was opened.
        console.log("Offline model download dialog opened.");
        break;
      case "download_success":
        // On Android 14+, model was succesfully downloaded.
        console.log("Offline model downloaded successfully!");
        break;
      case "download_canceled":
        // On Android 14+, the download was canceled by a user interaction.
        console.log("Offline model download was canceled.");
        break;
  })
  .catch((err) => {
    console.log("Failed to download offline model!", err.message);
  });

The device will display a dialog to download the model. Once the model is downloaded, you can use the getSupportedLocales function to get the list of installed locales.

`setCategoryIOS({...}): void` (iOS only)

This function is an implementation of AVAudioSession.setCategory for iOS. For multimedia applications, you may want to set the audio session category and mode to control the audio routing.

Note

When starting speech recognition, the audio session category is changed to playAndRecord with option defaultToSpeaker and allowBluetooth and mode measurement. You can instead configure the audio session category and mode by passing the iosCategory option to the start(..) function.

import {
  setCategoryIOS,
  AVAudioSessionCategory,
  AVAudioSessionCategoryOptions,
  AVAudioSessionMode,
} from "expo-speech-recognition";

setCategoryIOS({
  category: AVAudioSessionCategory.playAndRecord, // or "playAndRecord"
  categoryOptions: [
    AVAudioSessionCategoryOptions.defaultToSpeaker,
    AVAudioSessionCategoryOptions.allowBluetooth,
  ],
  mode: AVAudioSessionMode.default,
});

`getAudioSessionCategoryAndOptionsIOS()` (iOS only)

Returns the current audio session category and options. For advanced use cases, you may want to use this function to safely configure the audio session category and mode.

import { getAudioSessionCategoryAndOptionsIOS } from "expo-speech-recognition";

const values = getAudioSessionCategoryAndOptionsIOS();
console.log(values);
// { category: "playAndRecord", categoryOptions: ["defaultToSpeaker", "allowBluetooth"], mode: "measurement" }

`setAudioSessionActiveIOS(value: boolean, options?: { notifyOthersOnDeactivation: boolean }): void`

Sets the audio session active state.

import { setAudioSessionActiveIOS } from "expo-speech-recognition";

setAudioSessionActiveIOS(true, {
  notifyOthersOnDeactivation: true,
});

Name		Name	Last commit message	Last commit date
Latest commit History 139 Commits
.github/workflows		.github/workflows
android		android
example		example
images		images
ios		ios
src		src
.eslintrc.js		.eslintrc.js
.gitignore		.gitignore
.npmignore		.npmignore
.prettierignore		.prettierignore
README.md		README.md
app.plugin.js		app.plugin.js
expo-module.config.json		expo-module.config.json
package-lock.json		package-lock.json
package.json		package.json
tsconfig.json		tsconfig.json

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🎙️ expo-speech-recognition

Table of Contents

Installation

Important Note for Expo Beginners

Best Practices for Version Control

Usage

Using Hooks

Permissions

Direct module API

Speech Recognition Events

Handling Errors

Persisting Audio Recordings

Transcribing audio files

Supported input audio formats

Android

iOS

File transcription example

Polyfilling the Web SpeechRecognition API

Muting the beep sound on Android

Improving accuracy of single-word prompts

Platform Compatibility Table

API Methods

start(options: SpeechRecognitionOptions): void

stop(): void

abort(): void

requestPermissionsAsync(): Promise<PermissionResponse>

getPermissionsAsync(): Promise<PermissionResponse>

getStateAsync(): Promise<SpeechRecognitionState>

addSpeechRecognitionListener(eventName: string, listener: (event: any) => void): { remove: () => void }

getSupportedLocales(): Promise<{ locales: string[]; installedLocales: string[] }>

getSpeechRecognitionServices(): string[] (Android only)

getDefaultRecognitionService(): { packageName: string } (Android only)

getAssistantService(): { packageName: string } (Android only)

supportsOnDeviceRecognition(): boolean

supportsRecording(): boolean (Android only)

androidTriggerOfflineModelDownload({ locale: string }): Promise<{ status: "opened_dialog" | "download_success" | "download_canceled", message: string }>

setCategoryIOS({...}): void (iOS only)

getAudioSessionCategoryAndOptionsIOS() (iOS only)

setAudioSessionActiveIOS(value: boolean, options?: { notifyOthersOnDeactivation: boolean }): void

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`start(options: SpeechRecognitionOptions): void`

`stop(): void`

`abort(): void`

`requestPermissionsAsync(): Promise<PermissionResponse>`

`getPermissionsAsync(): Promise<PermissionResponse>`

`getStateAsync(): Promise<SpeechRecognitionState>`

`addSpeechRecognitionListener(eventName: string, listener: (event: any) => void): { remove: () => void }`

`getSupportedLocales(): Promise<{ locales: string[]; installedLocales: string[] }>`

`getSpeechRecognitionServices(): string[]` (Android only)

`getDefaultRecognitionService(): { packageName: string }` (Android only)

`getAssistantService(): { packageName: string }` (Android only)

`supportsOnDeviceRecognition(): boolean`

`supportsRecording(): boolean` (Android only)

`androidTriggerOfflineModelDownload({ locale: string }): Promise<{ status: "opened_dialog" | "download_success" | "download_canceled", message: string }>`

`setCategoryIOS({...}): void` (iOS only)

`getAudioSessionCategoryAndOptionsIOS()` (iOS only)

`setAudioSessionActiveIOS(value: boolean, options?: { notifyOthersOnDeactivation: boolean }): void`

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