I've had mixed results.

I had a good 8 pointer trotting by me really slowly in '06....and I got caught sitting down....bow on the hook. I "mahhh'd" to stop him....and didn't have time to get a shot off. I made a mistake. I SHOULD HAVE not made a sound and just accepted "defeat". What I did was I alerted him to my position....and I didn't see him in that vicinity again all season.

Fast-forward to 11/6/07.....and the SAME buck is coming in from behind me and to my right. I get to a shooting position as he passes behind me mere feet from my tree. He came to a stop (undera sapling)at less than 10yds and stood there looking at the few does that were also under me. When he went to dog one of the does....I again tried to "mahhh" to stop him. No dice. I tried it louder....and he stopped.

I nailed him.