We have Muscovy ducks, and they do make some noise, but it is certainly not as loud as a rooster. Females make a quack sound, but usually only when they are chasing each other.
Males make a whispery sound.
It sounds like they are trying to quack but they have a sore throat. At night they usually sleep, so you shouldn't have to worry about noise. The most noise they make is during mating season when the male is trying to mount the female. The females are slightly smaller at 8-12 pounds. If you live in the city, you may want to consider a smaller bird.