Ah this is about tennis eh ? Cryptic OPs.
I read somewhere that they are trained to expel air on the hit in order to hit harder. If true I can't see how it can be considered cheating, the opponent will be focused on the ball anyway and filter out shouts.
As for spectators getting the hump, appreciate they provide finance, but they are paying for the privilege of seeing the game, not dictate it. Surely players giving their best performance is the prime concern.
Maybe ask the BBC to buy and use a grunt filter ?