NYU Langone specialists are experienced at distinguishing different types of hearing loss, a reduction in a person’s ability to perceive sound. Hearing loss can affect people of any age, though it is most common in adults over age 60.
Hearing loss may be accompanied by a ringing or other sound in the ears, called tinnitus; a feeling of dizziness or spinning, called vertigo; or a sensation of pressure or pain in the ears. Not being able to hear high-pitched sounds such as a ringing telephone or the beep of an alarm may be an early sign of hearing loss.
The causes and symptoms of hearing loss fall into three categories: sensorineural hearing loss, conductive hearing loss, and mixed hearing loss. Our otolaryngologists—also known as ear, nose, and throat (ENT) physicians—work closely with audiologists, who are specialists in the diagnosis of hearing disorders, to evaluate your ears and the overall quality of your hearing to determine which type of hearing loss is causing your symptoms.
Sensorineural hearing loss usually happens gradually and affects both ears. This type of hearing loss is often caused by decreased function of the cochlea, the part of the inner ear that processes sound.
Inside the cochlea are bundles of cells covered in hair-like sensory receptors. These so-called hair cells detect sound vibrations as they travel through the inner ear and convert them to electrical signals before sending them to the brain. The brain interprets these signals as sound. If hair cells within the cochlea are damaged, fewer sound signals reach the brain, and noises or speech may seem muted or faint, even when close by.
Aging is the most common cause of degeneration in these sensory cells, but illness or repeated exposure to loud noise may also affect how hair cells function. More rarely, some types of medication, such as certain chemotherapy drugs to treat cancer and loop diuretics to treat kidney or heart disease, may cause hearing loss.
Less frequently, sensorineural hearing loss may occur in just one ear as the result of damage to the eighth cranial nerve, which is the nerve pathway that carries information about sound from the inner ear to processing centers in the brain. If the eighth cranial nerve is injured, it can’t convey information from the inner ear efficiently, resulting in hearing loss on one side.
Hearing loss may result from traumatic brain injury, which is often caused by a blunt force trauma to the head or another external force. Hearing loss from this kind of injury may pass quickly or persist for some time. It may also be accompanied by symptoms such as imbalance or weakness.
A brain tumor is another possible cause of damage to the eighth cranial nerve. Noncancerous tumors called acoustic neuromas are more common than cancerous tumors. As a tumor grows, it diverts nutrient-rich blood away from the nerve, which depletes healthy nerve cells. An acoustic neuroma may also press on areas within the brain stem as it grows, which may affect how sound signals travel between the brain and inner ear.
Acoustic neuromas are not life threatening and grow slowly. If you experience hearing loss—in particular, if hearing loss develops in one ear and not the other—our experts can determine whether an acoustic neuroma may be the cause.
Conductive hearing loss is less common than sensorineural hearing loss. Conductive hearing loss is caused by changes to the middle or outer ear.
The middle ear consists of the eardrum, plus three small bones that connect the middle ear to the inner ear. The outer ear consists of the rounded top part of the ear made of skin and cartilage that you can see, as well as the short inner canal that brings sounds from the outside to the middle ear.
Working together, the middle and outer ear convert external sound waves to mechanical vibrations and send these vibrations to the inner ear, where they are translated into electrical signals to be interpreted by the brain. Injury to these delicate systems interrupts the flow of sound waves and electrical signals and results in poor hearing. Any damage to the middle or outer ear may cause conductive hearing loss.
An ear infection, also called otitis media, affects the middle ear and is often caused by a buildup of fluid. Frequent ear infections may prevent structures in the middle ear from working properly and can cause short-term hearing loss. Most of the time, hearing returns after the infection has gone away.
A condition called otosclerosis can also cause conductive hearing loss. Otosclerosis prevents the bone structure in the middle ear from receiving and translating sound waves properly. It can lead to stapes fixation, in which the tiny stapes bone in the middle ear doesn’t allow sound waves to pass. Otosclerosis may develop in one or both ears.
Injury to the middle ear can occur from something as simple as inserting a cotton swab too far into the ear, rupturing the eardrum. Even an extremely loud noise like a gunshot or an explosion can overwhelm and damage the eardrum.
Earwax, an oily substance also known as cerumen that lubricates the skin inside of the ear canal, may build up and cause conductive hearing loss. Our doctors can safely remove earwax and improve hearing.
Doctors diagnose mixed hearing loss if damage has occurred in the inner ear as well as the middle or outer ear. A diagnosis of sensorineural hearing loss and conductive hearing loss in the same ear is considered mixed hearing loss.
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