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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 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 API The 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 | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
SpeechRecognitionAlternative | Chrome
Full support
33
| Edge ? | Firefox No support No | IE No support No | Opera No support No | Safari No support No | WebView Android
Full support
Yes
| Chrome Android
Full support
Yes
| Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android ? |
confidence | Chrome
Full support
33
| Edge ? | Firefox No support No | IE No support No | Opera No support No | Safari No support No | WebView Android
Full support
Yes
| Chrome Android
Full support
Yes
| Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android ? |
transcript | Chrome
Full support
33
| Edge ? | Firefox No support No | IE No support No | Opera No support No | Safari No support No | WebView Android
Full support
Yes
| Chrome Android
Full support
Yes
| Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android ? |
Legend
- Full support
- Full support
- No support
- No support
- Compatibility unknown
- Compatibility unknown
- 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"