Which condition is commonly associated with a Type As tympanogram?

A Type As tympanogram is characterized by a peak at below normal ear canal pressure and a significantly reduced peak admittance (the amount of sound energy that passes through the system), indicating that the mobility of the tympanic membrane (eardrum) is decreased. This decreased mobility is commonly associated with otosclerosis, a condition where there is abnormal bone growth in the middle ear that affects the ossicles (the small bones that transmit sound).

Otosclerosis can lead to conductive hearing loss because the stapes (one of the ossicles) becomes fixed in place and cannot move properly, which in turn limits the movement of the eardrum and reduces the admittance measured during tympanometry. Therefore, the presence of a Type As tympanogram is a strong indicator of otosclerosis and its impact on the normal functioning of the middle ear mechanics.

In contrast, conditions like middle ear infections and fluid in the ear typically produce a Type B tympanogram, which shows a flat response indicating poor mobility due to fluid or other factors, while noise-induced hearing loss generally results in a Type A tympanogram reflecting normal middle ear function.