Hearing loss can be categorized into three main types: conductive, sensorineural, or mixed (a combination of the other two). In conductive hearing loss, sound waves are not able to reach the inner ear hearing structures at normal levels. In sensorineural hearing loss, the sound conduction mechanism can be normal, but the inner ear hearing organ or hearing nerve is not functioning properly. These different types of hearing loss can be due to problems with the external, middle and inner ears, as well as the brain.

Hearing loss due to problems with the external ear is usually conductive. The most common cause of hearing loss worldwide is earwax plugging the ear canal. The wax plug interferes with sound waves reaching the eardrum. Similarly, narrowing of the ear canal due to inflammation, bony growths, or from aural atresia will cause a conductive hearing loss. Problems with the eardrum can also interfere with the fidelity of sound transmission. A thickened, scarred, or torn eardrum can’t vibrate normally. This leads to a conductive hearing loss because sound loses energy as it passes through the eardrum.