It's also called the auditory tube, & when it's blocked, an earache can result
Eustachian tube ... Getting water in the 
ears will not cause an acute ear infection, unless the eardrum has a... [DOC] [TLE] Otitis media with effusion: MedlinePlus Medical Encyclopedia [PAR] The following can cause the Eustachian tube to close or become blocked: ... find 
OME while checking your child's ears after an ear infection has been treated.