I'm generally silent whenever i'm on the field, which hasn't escaped the attention of pretty much everyone else out there. The groundsman, when I made my debut for my club's second XI, subjected me to a tea break long lecture on the fact that i'm quiet and I shouldn't be because "you're one of us now", if I had a pound of every time he's lectured me on some aspect of the game, i'd be a millionaire at the age of 21. The oppo tend to equate my silence with a lack of confidence in the field so it isn't uncommon for them to look for me and actively try to hit where i'm stood, something the team uses to their advantage by shouting "on your toes" to which i'll start jumping (star jumps and the like), it tends to make batsmen think twice about aiming for me. When i'm batting I generally keep quiet apart from the obvious calls for runs but I will turn and make some comments at the keeper if he's trying to have a joke with me, I don't mind when its good natured.
Sledging is discouraged in my league though, owing to some fairly ugly incidents in the last 18 months or so. We had a first team cup game abandoned this year because two of the oppo decided to go too far and then decided to bring out the handbags because someone in our first team decided to answer back.