SpeechRecognition
This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.
The SpeechRecognition
interface of the Web Speech API is the controller interface for the recognition service; this also handles the SpeechRecognitionEvent
sent from the recognition service.
Constructor
SpeechRecognition.SpeechRecognition()
- Creates a new
SpeechRecognition
object.
Properties
SpeechRecognition
also inherits properties from its parent interface, EventTarget
.
SpeechRecognition.grammars
- Returns and sets a collection of
SpeechGrammar
objects that represent the grammars that will be understood by the currentSpeechRecognition
. SpeechRecognition.lang
- Returns and sets the language of the current
SpeechRecognition
. If not specified, this defaults to the HTMLlang
attribute value, or the user agent's language setting if that isn't set either. SpeechRecognition.continuous
- Controls whether continuous results are returned for each recognition, or only a single result. Defaults to single (
false
.) SpeechRecognition.interimResults
- Controls whether interim results should be returned (
true
) or not (false
.) Interim results are results that are not yet final (e.g. theSpeechRecognitionResult.isFinal
property isfalse
.) SpeechRecognition.maxAlternatives
- Sets the maximum number of
SpeechRecognitionAlternative
s provided per result. The default value is 1. SpeechRecognition.serviceURI
- Specifies the location of the speech recognition service used by the current
SpeechRecognition
to handle the actual recognition. The default is the user agent's default speech service.
Event handlers
SpeechRecognition.onaudiostart
- Fired when the user agent has started to capture audio.
SpeechRecognition.onaudioend
- Fired when the user agent has finished capturing audio.
SpeechRecognition.onend
- Fired when the speech recognition service has disconnected.
SpeechRecognition.onerror
- Fired when a speech recognition error occurs.
SpeechRecognition.onnomatch
- Fired when the speech recognition service returns a final result with no significant recognition. This may involve some degree of recognition, which doesn't meet or exceed the
confidence
threshold. SpeechRecognition.onresult
- Fired when the speech recognition service returns a result — a word or phrase has been positively recognized and this has been communicated back to the app.
SpeechRecognition.onsoundstart
- Fired when any sound — recognisable speech or not — has been detected.
SpeechRecognition.onsoundend
- Fired when any sound — recognisable speech or not — has stopped being detected.
SpeechRecognition.onspeechstart
- Fired when sound that is recognised by the speech recognition service as speech has been detected.
SpeechRecognition.onspeechend
- Fired when speech recognised by the speech recognition service has stopped being detected.
SpeechRecognition.onstart
- Fired when the speech recognition service has begun listening to incoming audio with intent to recognize grammars associated with the current
SpeechRecognition
.
Methods
SpeechRecognition
also inherits methods from its parent interface, EventTarget
.
SpeechRecognition.abort()
- Stops the speech recognition service from listening to incoming audio, and doesn't attempt to return a
SpeechRecognitionResult
. SpeechRecognition.start()
- Starts the speech recognition service listening to incoming audio with intent to recognize grammars associated with the current
SpeechRecognition
. SpeechRecognition.stop()
- Stops the speech recognition service from listening to incoming audio, and attempts to return a
SpeechRecognitionResult
using the audio captured so far.
Examples
In our simple Speech color changer example, we create a new SpeechRecognition
object instance using the SpeechRecognition()
constructor, create a new SpeechGrammarList
, and set it to be the grammar that will be recognised by the SpeechRecognition
instance using the SpeechRecognition.grammars
property.
After some other values have been defined, we then set it so that the recognition service starts when a click event occurs (see SpeechRecognition.start()
.) When a result has been successfully recognised, the SpeechRecognition.onresult
handler fires, we extract the color that was spoken from the event object, and then set the background color of the <html>
element to that colour.
var grammar = '#JSGF V1.0; grammar colors; public <color> = aqua | azure | beige | bisque | black | blue | brown | chocolate | coral | crimson | cyan | fuchsia | ghostwhite | gold | goldenrod | gray | green | indigo | ivory | khaki | lavender | lime | linen | magenta | maroon | moccasin | navy | olive | orange | orchid | peru | pink | plum | purple | red | salmon | sienna | silver | snow | tan | teal | thistle | tomato | turquoise | violet | white | yellow ;' var recognition = new SpeechRecognition(); var speechRecognitionList = new SpeechGrammarList(); speechRecognitionList.addFromString(grammar, 1); recognition.grammars = speechRecognitionList; //recognition.continuous = false; recognition.lang = 'en-US'; recognition.interimResults = false; recognition.maxAlternatives = 1; var diagnostic = document.querySelector('.output'); var bg = document.querySelector('html'); document.body.onclick = function() { recognition.start(); console.log('Ready to receive a color command.'); } recognition.onresult = function(event) { 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 'SpeechRecognition' in that specification. |
Draft |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 33 [1] | 44 (44) [2] | Not supported | Not supported | Not supported |
continuous |
33 [1] | Not supported | Not supported | Not supported | Not supported |
Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | ? | (Yes)[1] | ? | 2.5 | Not supported | Not supported | Not supported |
continuous |
? | (Yes)[1] | ? | Not supported | Not supported | Not supported | Not supported |
- [1] Speech recognition interfaces are currently prefixed in Chrome, so you'll need to prefix interface names appropriately, e.g.
webkitSpeechRecognition
; You'll also need to serve your code through a web server for recognition to work. - [2] Can be enabled via the
media.webspeech.recognition.enable
flag in about:config, although note that currently speech recognition won't work on Desktop Firefox — it will be properly exposed soon, once the required internal permissions are sorted out.
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
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/speechrecognition