expo-stt

• Unofficial Speech To Text module for Expo which supported iOS and Android
• Forked anhtuank7c/expo-stt
• Migrated react-native-voice functionality on crossplatformkorea/expo-stt, which is forked from anhtuank7c/expo-stt
• Currently, anhtuank7c/expo-stt has a separate Google voice recognition modal. Instead, I migrated the react-native-voice code onto crossplatformkorea/expo-stt, which was created with the expo module, to use the built-in microphone like react-native-voice.

Sequence Diagram

Below is a sequence diagram explaining how each module, including SpeechRecognizer, works.

And below is the mermaid code to create the above diagram.

sequenceDiagram
    participant User
    participant ExpoSttModule
    participant SpeechRecognizer
    participant ReactNative as React Native Module

    User->>ExpoSttModule: startSpeech()
    ExpoSttModule->>SpeechRecognizer: createSpeechRecognizer()
    ExpoSttModule->>SpeechRecognizer: startListening()
    SpeechRecognizer-->>ExpoSttModule: onReadyForSpeech

    User->>SpeechRecognizer: User starts speaking
    SpeechRecognizer-->>ExpoSttModule: onBeginningOfSpeech
    ExpoSttModule->>ReactNative: sendEvent(onSpeechStart)

    User->>SpeechRecognizer: User finishes speaking
    SpeechRecognizer-->>ExpoSttModule: onEndOfSpeech
    ExpoSttModule->>ReactNative: sendEvent(onSpeechEnd)

    SpeechRecognizer-->>ExpoSttModule: onResults
    ExpoSttModule->>ReactNative: sendEvent(onSpeechResult)

    alt SpeechRecognizer encounters an error
        SpeechRecognizer-->>ExpoSttModule: onError
        ExpoSttModule->>ReactNative: sendEvent(onSpeechError)
    end

Demo

Add the package to your npm dependencies

npm install expo-stt
or
yarn add expo-stt

Remember, this module doesn't support Expo Go. So for Expo project, you will need to generates native code (Bare React Native project can skip this step)

npx expo prebuild --clean

Configure for iOS (Bare React Native project only)

Run npx pod-install after installing the npm package.

Add missing permissions for iOS

Add following key to plugins of app.json in Expo project This is an optional, just use in case you want to customize the permission string

  "plugins": [
    [
      "expo-stt",
      {
        "microphonePermission": "Allow $(PRODUCT_NAME) to access your microphone",
        "speechRecognitionPermission": "Allow $(PRODUCT_NAME) to access your speech recognition"
      }
    ]
  ]

For Bare React Native project, you need to add these key to Info.plist in ios directory

  <key>NSMicrophoneUsageDescription</key>
  <string>Allow $(PRODUCT_NAME) to access your microphone</string>
  <key>NSSpeechRecognitionUsageDescription</key>
  <string>Allow $(PRODUCT_NAME) to access your speech recognition</string>

Usage

Register some listeners

  import * as ExpoStt from 'expo-stt';

  useEffect(() => {
    const onSpeechStart = ExpoStt.addOnSpeechStartListener(() => {
      setSpokenText("");
      setError(undefined);
      setRecognizing(true);
    });

    const onSpeechResult = ExpoStt.addOnSpeechResultListener(({ value }) => {
      setSpokenText(value.join());
    });

    const onSpeechError = ExpoStt.addOnSpeechErrorListener(({ cause }) => {
      setError(cause);
      setRecognizing(false);
    });

    const onSpeechEnd = ExpoStt.addOnSpeechEndListener(() => {
      setRecognizing(false);
    });

    return () => {
      onSpeechStart.remove();
      onSpeechResult.remove();
      onSpeechError.remove();
      onSpeechEnd.remove();
    };
  }, []);

There are some functions available to call such as:

• ExpoStt.startSpeech()
• ExpoStt.stopSpeech()
• ExpoStt.destroySpeech()
• ExpoStt.requestRecognitionPermission()
• ExpoStt.checkRecognitionPermission()

Take a look into example/App.tsx for completed example

Contributing

Contributions are very welcome! Please refer to guidelines described in the contributing guide.