I've no way of finding the reply again but watching live I'm pretty confident that the ball pitching caused the initial spike and then that was followed fairly quickly (accounting for slow motion) of the bat hitting ground.
Regarding the Warner dismissal I think he knew he hit it.
I take my...
It was the noise of the ball pitching (as it was so full). It really wasn’t hard to work out, trouble is you had Warne and Ponting commentating and they’re not the sharpest tools in the box.