Hearing loss

Hearing loss, which doctors also call hypoacusis, is not one single thing: it is divided into two types, conductive and sensorineural.

The difference lies in where the path of sound breaks down. In conductive hearing loss the failure is in the mechanical segment, anywhere between the auricle, the outer ear you can see, and the stapes, the last of the little bones of the middle ear; that segment transmits sound poorly toward the cochlea, the snail-shaped chamber where sound becomes a nerve signal. In sensorineural hearing loss, which is the more common of the two, the problem lies anywhere from the cochlea inward: in the cochlea itself, in the auditory nerve or in the central nervous system. In one the sound never arrives; in the other no one picks it up.

The causes of the conductive form run from the trivial to the serious: they can be otitis media with effusion, fluid collecting behind the eardrum, or a tumor of the nasopharynx. Precisely because the same symptom spans that range, recent-onset hearing loss is evaluated with full audiometry, the formal measurement of how much and how well a person hears.