I don't make much noise whilst I am playing with myself or masturbating (except perhaps a deep sigh of pleasure if I peel my foreskin right back to totally expose my glans) but I find it adds to my pleasure if I grunt quite loudly as I ejaculate.
I like to grunt in short sharp bursts (uuuhhh, uuuhhh, uuuhhh) as the spunk spurts out of my cock and I like to end up with a few satified aaaahhhhs as I squeeze out the last few dribbles