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 sole custody situations, the child's other parent (also known as the non-custodial parent) has neither physical nor legal custody rights, but may be entitled to periods of visitation with the child (though those visits may be supervised, especially in situations involving domestic violence or child abuse).