Yes, it's called pipping and it's when they start to get air into their lungs, giving them the ability to communicate with their mother and siblings prior to hatching. It takes hours for them to finish hatching and they'll be exhausted by the time they're finished. They'll sleep a lot while they're drying off and fluffing up and the yolk provides them with enough sustenance to get them through their first couple of days while they gain strength.