Edited by birdie.lee - 5/9/13 at 7:41am
If you dog is howling in response to the baby it isn't because the sounds is hurting him or bothering him. Howling is an instinctual response in dogs derived from wild wolves calling to each other across vast distances.
The baby's cries must be at a pitch the dog can hear and they are triggering this response. Your dog is simple communicating with the baby, that's all.