Yeah...once mine start pipping, peeping, chirping, rocking and finally hatching I tend to lose hours each day standing over the hatching eggs and willing those little chicks out into the world, cheering them on, bribing them...whatever works. I've seen first-hand how having at least one hatched chick in that incubator encourages others to become more active....usually. They definitely communicate with one another, but even when I've removed a lone hatchling while the rest of the eggs seemed to remain "asleep", that hatched chick would hear and communicate with the ones chirping within their eggs. I watched my little "Bosch" Bielefelder chick run to the edge of the brooder and begin chirping loudly and excitedly whenever he heard one of the chicks still in their egg begin chirping.