Voice Search, launched in 2008, was built to serve a wide variety of people, regardless of gender, age, and accents, or variations in pitch, pace, and other factors. Two years later, Google improved this service by offering personalized recognition, a more accurate model. The personalized recognition associates the recordings of the words the user asks Google to recognize with his/her Google account. These words are then used to build an accurate speech model.
The first time you use Voice Search, you’ll be presented with a dialog to turn on personalized recognition. Google takes your privacy seriously, so you can enable or disable personalized recognition at any time through the Google voice recognition settings on your phone. If you’d like to disassociate your voice recordings from your Google Account, you can do so through the Google Dashboard in the Speech section.
At the moment, the speech recognition feature is available for Google users in the United States in English, plans in the near future envisage other countries and other languages also. The requirement for the use of voice recognition is having Android 2.2 version or higher and the download of the latest version of Voice Search app from Android Market.
Starting this week, Google has also launched Google Latitude, an app used by 9 million users worldwide that share their location with friends. The latest developments of Google related to voice apps include Voice Search, Voice Input and Voice Actions available for mobile phones, enabling users to speak their web searches, compose emails and SMS by voice, direct calling for business and ask phones to play certain songs. See more info here.