The quietest chicken breed I have had by far was the Bantam Silkie. I had three little buff girls in a rabbit hutch in the city and they made sweet little noises but nothing the neighbors would identify as chicken sounds. My favorite breed is Buff Orpington and while they are very sweet and friendly, my girls made quite the noise when laying eggs. I don't recall how noisy my Cochins were but I'm curious as I've seen others list them as quiet. I may be moving to the city and be interested in stealth farming again!