I have 2 6 mos old Buff Orps that have not crowed yet. They were penned together but are now separated and there are no other senior roos preventing them from crowing so I don't know why they don't. They make all kinds of other noises so I know nothings wrong with thier voicebox or whatever. They don't even try to crow lol. They have plenty of hormones too. One tries to mate everything in sight including the dog and he mated one of the hens when he was only 4 weeks old, totally knew what he was doing too, the little pervo!