SpeechRecognitionAlternative

Experimental

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The SpeechRecognitionAlternative interface of the Web Speech API represents a single word that has been recognized by the speech recognition service.

Properties

SpeechRecognitionAlternative.transcript Read only
Returns a string containing the transcript of the recognized word.
SpeechRecognitionAlternative.confidence Read only
Returns a numeric estimate of how confident the speech recognition system is that the recognition is correct.

Examples

This code is excerpted from our Speech color changer example.

recognition.onresult = function(event) {
  // The SpeechRecognitionEvent results property returns a SpeechRecognitionResultList object
  // The SpeechRecognitionResultList object contains SpeechRecognitionResult objects.
  // It has a getter so it can be accessed like an array
  // The first [0] returns the SpeechRecognitionResult at position 0.
  // Each SpeechRecognitionResult object contains SpeechRecognitionAlternative objects that contain individual results.
  // These also have getters so they can be accessed like arrays.
  // The second [0] returns the SpeechRecognitionAlternative at position 0.
  // We then return the transcript property of the SpeechRecognitionAlternative object
  var color = event.results[0][0].transcript;
  diagnostic.textContent = 'Result received: ' + color + '.';
  bg.style.backgroundColor = color;
}

Specifications

Specification Status Comment
Web Speech API
The definition of 'SpeechRecognitionAlternative' in that specification.
Draft

Browser compatibility

BCD tables only load in the browser

Firefox OS permissions

To use speech recognition in an app, you need to specify the following permissions in your manifest:

"permissions": {
  "audio-capture" : {
    "description" : "Audio capture"
  },
  "speech-recognition" : {
    "description" : "Speech recognition"
  }
}

You also need a privileged app, so you need to include this as well:

  "type": "privileged"

See also