Eustachian tube

Ear infections are more common in children because their eustachian tubes are shorter, narrower, and more horizontal than in adults, making the movement of air and fluid difficult. Bacteria can become trapped when the tissue of the eustachian tube becomes swollen from colds or allergies. Bacteria trapped in the eustachian tube may produce an ear infection that pushes on the eardrum causing it to become red, swollen, and sore.