Types of hearing loss

Hearing loss affects about one out of every 10 Americans. For those over 65 years of age, the ratio is nearly one in three. Hearing loss has different types and varying degrees. Some hearing loss can be treated medically, while others may be permanent. Hearing loss is classified according to which part of the auditory system is affected. Generally hearing loss has three types: conductive, sensorineural and mixed.

Conductive Hearing Loss

Conductive hearing loss is the result of disorders in either the outer or middle ear, which prevent sound from getting to the inner ear. Voices and sounds may sound faint, distorted or both. Most conductive hearing loss can be helped medically or surgically if treated promptly.

Common causes:
• Infection of the ear canal or middle ear
• Fluid in the middle ear
• Perforation or scarring of the eardrum
• Wax build-up
• Dislocation of the ossicles (three middle-ear bones)
• Foreign objects in the ear canal
• Otosclerosis
• Unusual growths, tumors

Sensorineural Hearing Loss

Sensorineural hearing loss occurs when inner ear nerves become damaged and do not properly transmit their signals to the brain. Patients may complain that people seem to mumble or that they hear, but do not understand what is being said. The aging process is the most common cause of sensorineural hearing loss because as we get older, the inner ear nerves and sensory cells gradually die.

In addition to advancing age, sensorineural hearing loss can be caused by:
• Injury
• Excessive noise exposure
• Viral infections (such as measles or mumps)
• Ototoxic drugs (medications that damage hearing)
• Meningitis
• Diabetes
• Stroke
• High fever
• Ménière’s disease
• Acoustic tumors
• Heredity
Sensorineural hearing loss is the most common type of hearing loss among adults (occurs in 80 percent of adult cases). It is not often medically or surgically treatable. Most sensorineural hearing loss can be successfully treated with hearing aids.

Mixed Hearing Loss

If a hearing loss is the result of both conductive and sensorineural components, it is known as a mixed hearing loss.