My D'uccle's crow is pretty quiet...and short. It's not a full on cock-a-doodle-doo.
It's more like...cock-a-doo....but it's more...eee-ee-eeee
My Silkie crows allllllllll day and he's very loud!
My Ameracauna was worse. He had to find a new home after he tried to kill my D'uccle...poor Roo Boy! (I know his name sucks, but if you saw him and hung out with him, you would probably think Roo Roo, was a very fitting name...
Brahma's are typically labeled for being quiet/infrequent crowers. They inherit it from the Oriental Gamefowl in my opinion, which from my experience do not crow as much and when they do isn't heard far away due to it being short and deep.