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<div id="pageData-name" class="pageData">Speech Input API</div>
<!-- BEGIN AUTHORED CONTENT -->
<p id="classSummary">
The <code>chrome.experimental.speechInput</code> module provides
one-shot speech recognition to Chrome extensions.
This module is still experimental. For information on how to use experimental
APIs, see the <a href="experimental.html">chrome.experimental.* APIs</a> page.
</p>
<h2 id="manifest">Manifest</h2>
<p>You must declare the "experimental" permission in the <a
href="manifest.html">extension manifest</a> to use the speech input
API.
For example:</p>
<pre>{
"name": "My extension",
...
<b>"permissions": [
"experimental"
]</b>,
...
}</pre>
<h2 id="howToStart">How to start speech recognition</h2>
<p>To start recognizing speech an extension must call the <code>start()</code>
method. If provided, your callback will be called once recording has
successfully started. In case of error <code>chrome.extension.lastError</code>
will be set.</p>
<p>This API provides exclusive access to the default recording device to the
first extension requesting it. Consequently, any calls to <code>start()</code>
when the device is being used by another extension or web page will fail and set
<code>chrome.extension.lastError</code>. The message <code>requestDenied</code>
will be set if another extension in the same profile is making use of the API.
Otherwise <code>noRecordingDeviceFound</code>, <code>recordingDeviceInUse</code>
or <code>unableToStart</code> will be set depending on the situation.</p>
<p>To check whether recording is currently active, call the
<code>isRecording()</code> method. Please note that it only checks for audio
recording within Chrome.</p>
<h2 id="howToGetResults">How to get speech recognition results</h2>
<p>Listen to the <code>onResult</code> event to receive speech recognition
results.</p>
<pre>
var callback = function(result) { ... };
chrome.experimental.speechInput.onResult.addListener(callback);
</pre>
<p>The <code>result</code> object contains an array of
<a href="#type-SpeechInputResultHypothesis">SpeechInputResultHypothesis</a>
sorted by decreasing likelihood.</p>
<p>Recording automatically stops when results are received. It is safe to call
<code>start()</code> again from the results callback.</p>
<p>To handle errors during speech recognition listen for the
<code>onError</code> event.</p>
<pre>
var callback = function(error) { ... };
chrome.experimental.speechInput.onError.addListener(callback);
</pre>
</p>Recording will automatically stop in case of error.
It is safe to call <code>start()</code> again from the error callback.</p>
<h2 id="howToStop">How to stop recording</h2>
<p>To stop speech recognition call the <code>stop()</code> method. If provided,
the callback function will be called once recording has successfully stopped.
In case of error <code>chrome.extension.lastError</code> will be set.
</p>
<h2 id="otherFeatures">Other features</h2>
<ul><li>
<code>onSoundStart</code> - Event generated when start of sound is detected
(from previously being silent).
</li><li>
<code>onSoundEnd</code> - Event generated when end of sound is detected (a
continued period of silence).
</li></ul>
<h2 id="examples">Examples</h2>
<p>The following example illustrates how to show a JavaScript alert with the
most likely recognition result.</p>
<pre>
function checkStart() {
if (chrome.extension.lastError) {
alert("Couldn't start speech input: " + chrome.extension.lastError.message);
}
}
function recognitionFailed(error) {
alert("Speech input failed: " + error.code);
}
function recognitionSucceeded(result) {
alert("Recognized '" + result.hypotheses[0].utterance + "' with confidence " + result.hypotheses[0].confidence);
}
chrome.experimental.speechInput.onError.addListener(recognitionFailed);
chrome.experimental.speechInput.onResult.addListener(recognitionSucceeded);
chrome.experimental.speechInput.start({ "language": "en" }, checkStart);
</pre>
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