Mine make a goose like honk every now and then, but even that is not overly loud. As a rule, they are the quietest of my 5 breeds......I agree! Australorps are very smart!
I have read articles that call them stealth chickens. One person said she had hers for a couple of year when a neighbor peeked over the fence and said you have chickens? I have never heard them!
They are a great choice for a city chicken.