It's in the Siri options, and I did know about it. However, it only seems to work for me when I'm at the lock screen with the screen on. At any other time, Siri won't recognise I'm there.
Well I know about it now but I had no clue until this site posted it a few minutes ago. I just overlooked the feature completely when I turned Siri on.
Me either. I tried to figure out what I was "doing wrong" but I soon found it simply inconsistent so gave up on it. Too bad since it is a nice feature.
I do leave the option on, however. I find if I press and hold home button to access Siri, and then raise to speak, it always works and I can speak lower and hear the result in the phone speaker.