Why do tennis women grunt?

Its not just Russian tennis players who grunt; they do it all around this crazy grunting world. But tennis players grunt because they want to distract the opponent from hearing the

Many female players say their shrieks and grunts are involuntary. There is a new

i don't mind it too much if it's actually grunting because of the force they are using to hit the ball but azarenka was doing my head in with her whizzy laser type noise, it isn't