Web/API/SpeechRecognitionAlternative

This is an experimental technologyCheck 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 recognised by the speech recognition service.

Properties

SpeechRecognitionAlternative.transcript Read only

Returns a string containing the transcript of the recognised 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 APIThe definition of 'SpeechRecognitionAlternative' in that specification.	Draft

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
SpeechRecognitionAlternative Experimental'	Chrome Full support 33 Prefixed' Notes' Full support 33 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Edge Full support ≤79 Prefixed' Notes' Full support ≤79 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox No support No	IE No support No	Opera No support No	Safari No support No	WebView Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Chrome Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.
confidence Experimental'	Chrome Full support 33 Prefixed' Notes' Full support 33 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Edge Full support ≤79 Prefixed' Notes' Full support ≤79 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox No support No	IE No support No	Opera No support No	Safari No support No	WebView Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Chrome Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.
transcript Experimental'	Chrome Full support 33 Prefixed' Notes' Full support 33 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Edge Full support ≤79 Prefixed' Notes' Full support ≤79 Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox No support No	IE No support No	Opera No support No	Safari No support No	WebView Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Chrome Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.	Firefox Android No support No	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support Yes Prefixed' Notes' Full support Yes Prefixed' Notes' Prefixed' Implemented with the vendor prefix: webkit Notes' You'll need to serve your code through a web server for recognition to work.

Legend

Full support  

Full support

No support  

No support

Experimental. Expect behavior to change in the future.'

Experimental. Expect behavior to change in the future.

See implementation notes.'

See implementation notes.

Requires a vendor prefix or different name for use.'

Requires a vendor prefix or different name for use.

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

• Web Speech API

SpeechRecognitionAlternative by Mozilla Contributors is licensed under CC-BY-SA 2.5.