The ear includes the outer, middle, and inner ear. The type of hearing loss you have depends on what part (or parts) of your ear have damage. Hearing care specialists can tell which type you have and the best treatment for you. There are three main types of hearing loss: sensorineural, conductive, and mixed. Auditory neuropathy spectrum disorder is a fourth type of hearing loss. It is less common.
Sensorineural Hearing Loss
The inner ear helps with hearing and balance. It contains fluid and thousands of tiny hair cells inside. We hear sound when these hair cells move. They transform the vibrations into electrical signals that your brain interprets as sound. Different hair cells move with different sounds. When you damage the hair cells or the nerve, sensorineural hearing loss occurs. This is the most common form of hearing loss.
Sensorineural hearing loss is permanent. There is no way to repair the damaged hairs. It generally affects both ears, though it may not be equal. Hearing aids are usually beneficial to patients with this type of hearing loss.
There are many causes of sensorineural hearing loss. Aging and chronic exposure to noise are the biggest culprits. Most common causes include to following.
- Noise exposure, particularly loud noises
- Genetic predisposition (hereditary hearing loss)
- Head injury
- Structural malformation of the ear(s)
- Ototoxic drugs (drugs that are toxic to the ears)
Presbycusis is the most common cause of sensorineural hearing loss. It is a part of the natural aging process and occurs over time. It affects the ability to hear high pitched sounds. Presbycusis is progressive, and affects 30 to 40 percent of people over age 65. Noise-induced hearing loss can compound the effect of presbycusis. Hearing aids may be beneficial.
Sudden onset sensorineural hearing loss can either be immediate or over the course of a few days. The type of hearing loss requires immediate medical attention by an otologist. These are doctors specializing in diseases of the ear. Any delay may decrease the chances of effective treatment.
Conductive hearing loss
The middle ear starts at your eardrum at the end of the ear canal. The eardrum moves with sound, and different pitches make the eardrum move. The eardrum also makes the bones (ossicles) within it move. This sends a signal to the inner ear.
Conductive hearing loss is when sound can’t travel through the outer and middle ear. This makes soft sounds hard to hear and loud sounds seem muffled. It can affect one or both ears. Conductive hearing loss is not permanent and medicine or surgery can often repair it.
This type of hearing loss has many different causes, including:
- Otitis media (middle ear infection)
- Hole in the eardrum, such as a rupture
- Benign tumors
- Fluid in the middle ear from allergies, cold or flu viruses
- Earwax (cerumen) buildup
- A foreign object stuck in the outer ear
- Eustachian tube dysfunction
- Structural malformation of the ear
Mixed hearing loss
This type is what it sounds like. It is a mix of both sensorineural and conductive hearing loss. There may be damage in the outer or middle ear and the inner ear at the same time. Having both sensorineural and conductive hearing loss can make hearing loss worse.
This shares the same common causes with both sensorineural and conductive hearing loss. An example of this would be a ruptured eardrum from an ear infection and working around loud noises. Hearing aids may be beneficial for mixed hearing loss.
Auditory neuropathy spectrum disorder
Auditory neuropathy occurs when there is damage to the inner ear or the hearing nerve. This causes normal sound to enter the ear to in a way the brain cannot understand. The inner ear detects sound, but cannot send it to the brain.
This type of hearing disorder can affect people of any age. From the NIDCD, it is not known how many people have this. Researchers believe auditory neuropathies play a large role in hearing loss.
Degrees of hearing loss
Regardless of type, hearing loss has degrees ranging from mild to profound.
- Mild hearing loss results in soft sounds being hard to hear. You will be able to hear most speech sounds.
- Moderate hearing loss may lead to not being able to hear speech when someone is talking at a normal sound level.
- Severe hearing loss means that you cannot hear speech at a normal level. You may only be able to hear some loud noises.
- Someone experiencing profound hearing loss will be unable to hear any speech. They will only be able to hear very loud sounds.
Other hearing loss definitions
Hearing loss has many other clinical descriptions. We use these for further classification. The following are some of the more common descriptors.
- Unilateral: hearing loss in one ear
- Bilateral: hearing loss in both ears
- Pre-lingual: happened before a person learned to talk
- Post-lingual: happened after a person learned to talk
- Symmetrical: loss is the same in both ears
- Asymmetrical: loss is different in each ear
- Progressive: occurs over time
- Sudden: happens in a quick manner
- Fluctuating: gets better or worse over time
- Stable: stays the same over time
- Congenital: present at birth
- Acquired or delayed onset: appears later in life
See a hearing instrument specialist for more information about hearing loss. If you’d like to learn more about how hearing aids can help you, make an appointment today!