The noisiest chickens are the males, known as cockerels or roosters. They are territorial birds, and like shouting about it. A crowing cockerel is telling other males that these hens are all his, and at the same time he is telling the hens that he is still here (although judging by the lack of reaction this crowing makes among the hens, they don’t seem that impressed).
Chickens are not noisy - most of the time!
Cockerels do indeed tend to crow at sunrise. This is because chickens are early risers. The glimpse of dawn signals a new day for a proud cockerel, and he announces it for all the world to hear. This is why, in some ancient mythologies, the cockerel is associated with the sun god. His fondness for finding a high spot to cow from is also why he’s often found on weathervanes on churches and other tall buildings - a golden bird symbolising the sun and new day.
Hens make a lot of sounds, but most of them are quiet and gentle. The only time they get really loud are when they have laid an egg. It’s not known why many hens ‘shout about it’ after laying - but this is the ‘classic’ chicken sound someone makes when they want to impersonate a chicken!
Hens will sometimes call in the same way when no egg has been laid. It’s nothing to worry about, and is not a sign of illness or distress.
The only other time hens get loud is if they are spooked - the flapping, feather-rustling dash away from a perceived danger is accompanied by another ‘Bap-bap-badaaap!’ classic chicken sound!
Otherwise, a hen’s vocalisations are a quiet ‘Baaap’ and gentle clucking.