The current mechanic for a batted ball that hits the batter, based on the Mechanics Update posted on the SUP Central Hub (9/19/18) has now been changed to: When there is a dead ball call off the batter on a swing – the “delay” by the base umpire is no longer necessary – call the dead ball when you observe the play.

Although removed from the 2012 CCA Manual, the mechanic continued to be as stated in the 2011 Manual – the base umpires should hesitate and let the plate umpire make this call. It was worded:
“This call belongs primarily to the plate umpire, but a base umpire who sees the batter hit with her own batted ball, and the plate umpire has not made the call, should rule the ball dead. The ball is either foul or the batter is out but that judgment must be made solely by the plate umpire using the batter’s whereabouts when he lost sight of the ball as his guide – the only time the ball could have hit her without his seeing it. Only the plate umpire determines the result of the call.”

It was also stated at the 2011 NCAA Clinic that the base umpires should hesitate, give the plate umpire a chance to call it, and then if it is not called,come up big and loud.

Plate umpire mechanics for this situation (added to the 2010 manual)
There is no hurry to make this call if you are not sure. If you think you saw something but are not quite sure, just let the play continue. If the batted ball did hit the batter, your partners will kill the ball, or no umpire saw it, so it did not happen.

The plate umpire knows that if a partner saw a batter hit with her own batted ball that he/she did not call, that base umpire would call it after the proper hesitiation. So there is no help to get on this play. Simply tell the coach “If my partners had seen the ball hit her, they would have called it. Apparently they did not see the ball hit her. I did not see the ball hit her. Therefore, the ball stays live and the play stands.”

Notice the language. The umpire did not say that the ball did not hit the batter. The umpire said that neither she nor her partners saw the ball hit the batter.

Here is the history on this “Lost Mechanic”
2006 – 2009: This call can be made by any umpire, but base umpires should make the call only if the plate umpire does not.
2010: A new section was added with the wording listed above.
2011: same wording as 2010
2012: major changes made to manual. This mechanic was removed.
2012-2018: mechanic continued to be for the base umpire(s) to hesitate before making the call.
2018: Mechanics Update posted (9/19/18) on the SUP Central Hub, as listed above

Batter hits the ball twice while bat is still in batter’s hands
This is a very similar play to the above. Use the same mechanics.