My Silkie has a deep, soft, almost baritone crow. We nicknamed him The Melancholy Rooster, because he always sounds so sad! My Bantam Nankins have a shrill, almost piercing crow, but it's not terribly loud, all things considered (and with that piercing note, I am sincerely grateful for the softer volume!)
My sister's RIR, on the other hand is still going and crowing VERY loudly at ten years old. Tyson has the loudest, most obnoxious crow I've ever heard. Unfortunately, he's got the temperament to match, but since he lives on a busy dairy farm, replete with numerous (fixed) cats, a chicken-eating hound, coons, opossums and coyotes, he's always got a reason to sound off ... or at least HE thinks he does!
Those are HIS hens, in HIS territory and it's his bounden duty to let the world know it ... ad nauseum!