SEROUS OTITIS MEDIA
This can be either short term often as a result of a recent middle ear infection (Acute Otitis Media) or more of chronic condition defined as when the fluid persists for more than a 3 month period.
Acute or chronic serous otitis media is common in children and we tend to outgrow the issue as the Eustachian tube enlarges after age 4+.
The main symptoms of an abnormal middle ear pressure include a clogged or fullness sensation in the ear and muffled or decreased hearing (Conductive Hearing Loss).
Occasionally, fluid can build up in the middle ear space due to these abnormal pressure dynamics. This is common in children but can also occur in adults, especially when flying or diving while congested (a problem known as otic barotrauma).
See Ear Fluid / Serous Effusion for more information