The Eustachian tube connects the throat and the middle ear (the site of a typical  ear infection ) and allows air to travel between them and equalize the pressures. When the Eustachian tube is temporarily pinched off, pressure can build up in the middle ear.
Visitation is a matter of state law, but generally speaking, every state allows parents to exercise a reasonable amount of visitation with their children, which generally means enough time to establish and maintain a meaningful relationship.
Quick Answer. A residential custodial parent is a parent who has sole physical custody of his child as ruled by a court. In these situations, the other parent does not have shared or joint custody over the child. The child lives with the residential custodial parent the majority of the time. Most states have two different types of custody: legal and physical.