You'd be surprised at the difference between listening to the crowd through the tv and being on the pitch itself. A lot of the time you will not hear whistles from the crowd on the pitch - the other noise (boos/chants/singing/etc) drowns it out, and the referee's whistle is much more audible above this.
But I guess that adding a helmet with padding and some football players not used to whistling and it may well get a bit confusing.
I'd rather die peacefully in my sleep like my Grandfather,
than screaming in terror like his passengers.- Jim Harkinshttp://www.Horrible.Demon.co.uk/