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.
In general, a fixed visitation scheduled is one where the judge orders times (and sometimes places) where the non-custodial parent is to have parental visitation. For example, a non-custodial parent could have visitation rights on Monday and Wednesday nights, or only on holiday weekends.