Carrie,
I myself used to breed and show Cochin Bantams and Frizzle Cochin Bantams. And from experience I can tell you that some Cochin roosters will never crow. If they are very laid back and easy going then they might not ever crow and if so it could be very rare. And if they are down in the pecking order they wont crow as much, crowing I think(dont take my word for it I am no expert) is a sign of dominance in a flock and if there is more than 1-2 males in a flock only the alpha male(s) will crow on a regular basis to show dominace to the other males. And with Cochins, I have raised birds from eggs and have had several that have never crowed at all, not to say they couldnt but they just never did and if so I never heard or saw them. It just happens, kinda like a hen trying to crow. They still acted like a macho in front of the ladies and done their little mating dance thing but never crowed. And the ones I noticed that didnt crow were also some of my best showers. Hope my two cents has helped.
~Casey