Pertaining to a medical condition involving the absence of one or both ear canals. In the case of both ear canals being closed, the condition is often simply called "Bilateral Atresia."

Congenital aural atresia is often a result of an interruption of normal fetal development during the first trimester, between four and six weeks, when ear structures, heart valves, the spinal column, and some facial characteristics are also developing. Consequently, people with aural atresia may also have other defining characteristics, like pulmonary stenosis, mandibulofacial dysostosis, etc.

To facilitate hearing, individuals born with this condition may use a bone conduction hearing aid. This device has a battery-run microphone on one end, and an oscillator on the other. The oscillator rests on the side of the head, behind the ear, on the mastoid bone, where it sends vibrations through the skull, and into the inner ear. In the case of bilateral atresia, this may be the only way the individual can hear in normal circumstances.

I was born with bilateral atresia of the ears, and thought that it might make a good beginning writeup... more on this later, if I have time =)