I've just got 4, so it's all a bit new.
3 go cluck, cluck when you talk to them, but otherwise are very quiet. Except when laying an egg, then they proudly announce it to the whole village 
The other sqwarks regularly. Every 20 seconds approximately. She sounds half clucky/half cockerel like a "bwark!" but it is loud.
I'm worried that someone will complain and I'll have to get rid of them all :(
Can you shut a chicken up? 