SpeechRecognition#

The SpeechRecognition interface provides a high-level API for performing speech recognition. It supports real-time speech recognition and recognition of audio files, offering flexibility in a variety of use cases.

Features Overview#

• Real-Time Recognition: Transcribe live audio from the microphone.
• File-Based Recognition: Analyze and transcribe recorded audio files.
• Multi-Language Support: Specify the recognition locale for different languages.
• Intermediate Results: Access partial and final results for progressive transcription.
• Custom Callbacks: Handle transcription results and sound level changes with event listeners.

Type Definitions#

RecognitionTaskHint#

Hints for the type of task for which speech recognition is used:

• 'confirmation': For commands like "yes," "no," or "maybe."
• 'dictation': For tasks similar to keyboard dictation.
• 'search': For identifying search terms.
• 'unspecified': For general-purpose speech recognition.

SpeechRecognitionResult#

Represents the result of speech recognition:

• isFinal: Indicates if the transcription is complete and final.
• text: The transcription as a user-displayable string, with the highest confidence level.

Static Properties#

Supported Locales#

• supportedLocales: Returns a list of locales supported by the speech recognizer, such as "en-US", "fr-FR", or "zh-CN".

Recognition State#

• isRecognizing: Indicates whether a recognition request is currently active.

Methods#

Start Real-Time Recognition#

start(options: object): Promise<boolean>
Starts speech recognition from the device microphone.

Options#

• locale: Locale string for the desired language (optional).
• partialResults: Return intermediate results (default: true).
• addsPunctuation: Automatically add punctuation to results (default: false).
• requestOnDeviceRecognition: Keep audio data on the device (default: false).
• taskHint: Specify the recognition task type ('confirmation', 'dictation', 'search', 'unspecified').
• useDefaultAudioSessionSettings: Use default audio session settings (default: true).
• onResult: Callback for recognition results (SpeechRecognitionResult).
• onSoundLevelChanged: Callback for sound level changes (optional).

Example#

1await SpeechRecognition.start({
2  locale: "en-US",
3  partialResults: true,
4  addsPunctuation: true,
5  onResult: (result) => {
6    console.log("Transcription:", result.text)
7  },
8  onSoundLevelChanged: (level) => {
9    console.log("Sound Level:", level)
10  }
11})

Recognize Speech in Audio Files#

recognizeFile(options: object): Promise<boolean>
Starts recognition for a recorded audio file.

Options#

• filePath: Path to the audio file.
• locale: Locale string for the desired language (optional).
• partialResults: Return intermediate results (default: false).
• addsPunctuation: Automatically add punctuation to results (default: false).
• requestOnDeviceRecognition: Keep audio data on the device (default: false).
• taskHint: Specify the recognition task type ('confirmation', 'dictation', 'search', 'unspecified').
• onResult: Callback for recognition results (SpeechRecognitionResult).

Example#

1await SpeechRecognition.recognizeFile({
2  filePath: FileManager.join(FileManager.documentDirectory, "example.wav"),
3  locale: "en-US",
4  addsPunctuation: true,
5  onResult: (result) => {
6    console.log("File Transcription:", result.text)
7  }
8})

Stop Recognition#

stop(): Promise<void>
Stops an active speech recognition session.

Example#

1await SpeechRecognition.stop()

Examples#

Real-Time Recognition with Progress Updates#

1await SpeechRecognition.start({
2  locale: "en-US",
3  onResult: (result) => {
4    console.log(result.isFinal ? "Final Result:" : "Partial Result:", result.text)
5  },
6  onSoundLevelChanged: (level) => {
7    console.log("Sound Level:", level)
8  }
9})

Recognize Audio File#

1await SpeechRecognition.recognizeFile({
2  filePath: FileManager.join(FileManager.documentDirectory, "audio.m4a"),
3  partialResults: false,
4  onResult: (result) => {
5    console.log("File recognition completed. Transcription:", result.text)
6  }
7})

Stop Active Recognition#

1if (await SpeechRecognition.start({
2  // ...
3})) {
4  // Stop after 10 seconds.
5  setTimeout(() => {
6    await SpeechRecognition.stop()
7  }, 10 * 1000)
8}

Notes#

• Ensure the necessary microphone or file access permissions are granted before using this API.
• Use supportedLocales to determine available languages for recognition.
• For optimal performance, use audio files in formats supported by iOS (e.g., .wav, .m4a).