What condition refers to an absent or closed-off ear canal?

Atresia refers specifically to a congenital condition in which the ear canal is either absent or abnormally closed off. This condition directly impacts the ability to transmit sound waves to the middle ear, leading to potential hearing loss. Atresia often presents significant challenges in hearing assessments and management because it affects the pathway required for sound conduction.

Otitis media, on the other hand, is an inflammation of the middle ear and does not involve an absent ear canal but rather refers to fluid accumulation and infection within the existing ear structures. Conductive hearing loss is a broader term that can be caused by various factors, including but not limited to atresia; it encompasses any condition that impedes sound conduction through the outer or middle ear. Eustachian tube dysfunction involves the inability of the tube to equalize pressure in the ear, which can affect hearing but does not concern the physical structure of the ear canal itself.

Thus, atresia stands out as the only condition directly describing the absence or closure of the ear canal.