Aural Atresia is the absence of an external ear canal. Usually patients are also lacking a middle ear space and eardrum. They may also have incomplete of misshaped ear bones. It is common for the inner ear and auditory nerve to be normal.
Some patients may have an ear canal, but it is narrower than usual. This is called canal stenosis.
Atresia is usually associated with microtia (an underdeveloped external ear), but can also rarely occur in isolation. Aural atresia most commonly affects just one ear (unilateral) but can also occur in both ears (bilateral).
All children with atresia have a degree of hearing loss. The extent of this hearing loss and how it affects your child (particularly in the case of unilateral atresia) will vary with every individual.
A child with bilateral Atresia has a minimum of a 55dB hearing loss in both ears. Normal conversational speech is usually between 40 to 50dB, which is quieter than what these children can hear. Therefore, for a child with bilateral atresia to develop normal speech and language, some kind of hearing aid must be worn.
Atresia is classified as a conductive hearing loss because there is a problem conducting sound from the external ear to the inner ear (because there is no canal for the sound to travel through).