If you opt into personalized recognition, we begin to associate the recordings of the words that you ask us to recognize with your Google account. We then automatically use these words to build a speech model specifically for you. This speech model enables us to deliver greater recognition accuracy. Although subtle, accuracy improvements begin fairly quickly and will build over time.
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.