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.
When a parent does not have physical custody, they may still have visitation rights. Visitation arrangements often proscribe a very specific schedule, such as the child or children spending the first and third weekends of the month with the non-custodial parent.