语音识别

Experimental

这是一个实验中的功能
此功能某些浏览器尚在开发中,请参考浏览器兼容性表格以得到在不同浏览器中适合使用的前缀。由于该功能对应的标准文档可能被重新修订,所以在未来版本的浏览器中该功能的语法和行为可能随之改变。

The SpeechRecognition interface of the Web Speech API is the controller interface for the recognition service; this also handles the SpeechRecognitionEvent (en-US) sent from the recognition service.

Note: On Chrome, using Speech Recognition on a web page involves a server-based recognition engine. Your audio is sent to a web service for recognition processing, so it won't work offline.

Constructor

SpeechRecognition.SpeechRecognition() (en-US)
Creates a new SpeechRecognition object.

Properties

SpeechRecognition also inherits properties from its parent interface, EventTarget.

SpeechRecognition.grammars (en-US)
Returns and sets a collection of SpeechGrammar objects that represent the grammars that will be understood by the current SpeechRecognition.
SpeechRecognition.lang (en-US)
Returns and sets the language of the current SpeechRecognition. If not specified, this defaults to the HTML lang attribute value, or the user agent's language setting if that isn't set either.
SpeechRecognition.continuous (en-US)
Controls whether continuous results are returned for each recognition, or only a single result. Defaults to single (false.)
SpeechRecognition.interimResults (en-US)
Controls whether interim results should be returned (true) or not (false.) Interim results are results that are not yet final (e.g. the SpeechRecognitionResult.isFinal property is false.)
SpeechRecognition.maxAlternatives (en-US)
Sets the maximum number of SpeechRecognitionAlternative (en-US)s provided per result. The default value is 1.
SpeechRecognition.serviceURI (en-US)
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.

Methods

SpeechRecognition also inherits methods from its parent interface, EventTarget.

SpeechRecognition.abort() (en-US)
Stops the speech recognition service from listening to incoming audio, and doesn't attempt to return a SpeechRecognitionResult.
SpeechRecognition.start() (en-US)
Starts the speech recognition service listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.
SpeechRecognition.stop() (en-US)
Stops the speech recognition service from listening to incoming audio, and attempts to return a SpeechRecognitionResult using the audio captured so far.

Events

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface.

audiostart
Fired when the user agent has started to capture audio.
Also available via the onaudiostart property.
audioend
Fired when the user agent has finished capturing audio.
Also available via the onaudioend property.
end
Fired when the speech recognition service has disconnected.
Also available via the onend property.
error
Fired when a speech recognition error occurs.
Also available via the onerror property.
nomatch
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 (en-US) threshold.
Also available via the onnomatch property.
result
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.
Also available via the onresult property.
soundstart
Fired when any sound — recognisable speech or not — has been detected.
Also available via the onsoundstart property.
soundend
Fired when any sound — recognisable speech or not — has stopped being detected.
Also available via the onsoundend property.
speechstart
Fired when sound that is recognised by the speech recognition service as speech has been detected.
Also available via the onspeechstart property.
speechend
Fired when speech recognised by the speech recognition service has stopped being detected.
Also available via the onspeechend property.
start
Fired when the speech recognition service has begun listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.
Also available via the onstart property.

Examples

In our simple Speech color changer example, we create a new SpeechRecognition object instance using the SpeechRecognition() (en-US) constructor, create a new SpeechGrammarList (en-US), and set it to be the grammar that will be recognised by the SpeechRecognition instance using the SpeechRecognition.grammars (en-US) 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() (en-US).) When a result has been successfully recognised, the SpeechRecognition.onresult (en-US) 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
SpeechRecognition
Draft  

Browser compatibility

BCD tables only load in the browser

See also