SpeechRecognition

{{APIRef("Web Speech API")}} 

The SpeechRecognition interface of the Web Speech API is the controller interface for the recognition service; this also handles the {{domxref("SpeechRecognitionEvent")}}  sent from the recognition service.

[!NOTE] On some browsers, like 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.

{{InheritanceDiagram}} 

Constructor

• {{domxref("SpeechRecognition.SpeechRecognition", "SpeechRecognition()")}} 
  • : Creates a new SpeechRecognition object.

Instance properties

SpeechRecognition also inherits properties from its parent interface, {{domxref("EventTarget")}} .

• {{domxref("SpeechRecognition.grammars")}} 
  • : Returns and sets a collection of {{domxref("SpeechGrammar")}}  objects that represent the grammars that will be understood by the current SpeechRecognition.
• {{domxref("SpeechRecognition.lang")}} 
  • : 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.
• {{domxref("SpeechRecognition.continuous")}} 
  • : Controls whether continuous results are returned for each recognition, or only a single result. Defaults to single (false.)
• {{domxref("SpeechRecognition.interimResults")}} 
  • : Controls whether interim results should be returned (true) or not (false.) Interim results are results that are not yet final (e.g. the {{domxref("SpeechRecognitionResult.isFinal")}}  property is false.)
• {{domxref("SpeechRecognition.maxAlternatives")}} 
  • : Sets the maximum number of {{domxref("SpeechRecognitionAlternative")}} s provided per result. The default value is 1.

Instance methods

SpeechRecognition also inherits methods from its parent interface, {{domxref("EventTarget")}} .

• {{domxref("SpeechRecognition.abort()")}} 
  • : Stops the speech recognition service from listening to incoming audio, and doesn’t attempt to return a {{domxref("SpeechRecognitionResult")}} .
• {{domxref("SpeechRecognition.start()")}} 
  • : Starts the speech recognition service listening to incoming audio with intent to recognize grammars associated with the current SpeechRecognition.
• {{domxref("SpeechRecognition.stop()")}} 
  • : Stops the speech recognition service from listening to incoming audio, and attempts to return a {{domxref("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 {{domxref("SpeechRecognitionAlternative.confidence","confidence")}}  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 — recognizable speech or not — has been detected. Also available via the onsoundstart property.
• soundend
  • : Fired when any sound — recognizable speech or not — has stopped being detected. Also available via the onsoundend property.
• speechstart
  • : Fired when sound that is recognized by the speech recognition service as speech has been detected. Also available via the onspeechstart property.
• speechend
  • : Fired when speech recognized 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 {{domxref("SpeechRecognition.SpeechRecognition", "SpeechRecognition()")}}  constructor, create a new {{domxref("SpeechGrammarList")}} , and set it to be the grammar that will be recognized by the SpeechRecognition instance using the {{domxref("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 {{domxref("SpeechRecognition.start()")}} .) When a result has been successfully recognized, the {{domxref("SpeechRecognition.result_event", "result")}}  event fires, we extract the color that was spoken from the event object, and then set the background color of the {{htmlelement("html")}}  element to that color.

const 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 ;";
const recognition = new SpeechRecognition();
const speechRecognitionList = new SpeechGrammarList();
speechRecognitionList.addFromString(grammar, 1);
recognition.grammars = speechRecognitionList;
recognition.continuous = false;
recognition.lang = "en-US";
recognition.interimResults = false;
recognition.maxAlternatives = 1;

const diagnostic = document.querySelector(".output");
const bg = document.querySelector("html");

document.body.onclick = () => {
  recognition.start();
  console.log("Ready to receive a color command.");
};

recognition.onresult = (event) => {
  const color = event.results[0][0].transcript;
  diagnostic.textContent = `Result received: ${color}`;
  bg.style.backgroundColor = color;
};

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Web Speech API