How to turn on 'Ok Google' detection

All of those nifty Google voice commands are one of the major strengths of using an Android phone. But they're even more powerful if you enable "Ok Google" detection from any screen. This means whether your phone is locked or you're using another app, you can just speak a question or command to put Google's search power to use. To start, launch the Google app and open Settings Ok Google detection. Next you'll be prompted to say, "Ok Google" three times so the app can learn how your voice sounds.