Voice Search for Google Chrome provides a method to search by speaking. It comes pre-loaded with servics such as: "Google, Wikipedia, YouTube, Bing, Yahoo, DuckDuckGo and Wolfram|Alpha." You can also add your own user-defined search engines. It also integrates a speech input button for all websites using HTML5 search boxes, all of the default search engines' websites, Facebook, Twitter, reddit, and GitHub.
If you're using Chrome 9 or higher, you may likely need to launch Chrome with --enable-speech-input launch flag. To do this on Windows, right click on your Google Chrome icon (shift+right click while Chrome is closed for Windows 7 if you've it pinned to the task bar), and set the target field to following: %LocalAppData%\Google\Chrome\Application\chrome.exe --enable-speech-input
In OSX, you've to create an Apple Script with following code and save it in ~/Applications/
do shell script "/Applications/Google\\ Chrome.app/Contents/MacOS/Google\\ Chrome --enable-speech-input"
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