Deafness and Hearing Loss: Types, Causes, and More

Deafness (profound hearing loss) is a condition where a person can’t hear anything or may only hear very loud sounds in one or both ears. Hearing loss that can lead to deafness is common, especially with age. You can also be born deaf or lose your hearing after infections or traumatic injuries to the ear. About half a million people in the United States are deaf.  

Your ear has three major sections that help convert sound waves to signals that are sent through a special auditory (hearing) nerve to your brain. Problems with these three areas of your ear or the auditory nerve can cause deafness.

Most causes of deafness are permanent. However, assistive technology like hearing aids and cochlear implants can help restore hearing in some people. Some Deaf people choose not to restore their hearing and prefer communication through sign language.

Deafness may be split into different categories based on the source of the hearing loss. These categories include the following.

Conductive Hearing Loss 

This type of hearing loss is caused by a problem with sound waves traveling through your outer or middle ear. You may hear muffled sounds. 

Sensorineural Hearing Loss 

This type of hearing loss is caused by a problem with your inner ear or auditory nerve. Your sound may be distorted or muffled. 

Mixed Hearing Loss 

Some people have hearing loss due to problems with multiple parts of their ear. People with both conductive and sensorineural hearing loss have mixed hearing loss. 

Auditory Neuropathy Spectrum Disorder

Once sound signals reach the inner ear, they travel to the brain through a special nerve for hearing called the auditory nerve. People with auditory neuropathy spectrum disorder have problems with the inner ear or the nerve that sends the signal to the brain. With this disorder, your brain may not be able to process and understand the sound even if it enters your ear normally. 

Hearing requires the conversion (changing) of sound waves to signals that your brain can understand. Your ear has three major sections that help with this process: the outer, middle, and inner. An auditory nerve relays the signal from your inner ear to your brain. This process is complex and requires many parts working together. 

Most hearing loss happens as you get older. That’s because age can affect special types of cells in your inner ear that are important for hearing. Older age is also associated with problems in sound waves traveling from the middle ear to the inner ear.

In children, about 50% of hearing loss is related to genetics. You can also be born deaf if your birth parent had certain infections or was exposed to specific chemicals.

Ear infections and trauma to the ear can also cause deafness.

Risk Factors

Several risk factors can make deafness more likely. These risk factors include:

• Advancing age
• Exposure to mumps, meningococcal infections, or cytomegalovirus (CMV) before birth 
• Down syndrome
• Frequent or prolonged exposure to loud noise
• Frequent ear infections
• Genetic mutations associated with deafness

Not everyone experiences deafness the same way. Although some Deaf people can’t hear any sound, most Deaf people have some form or amount of hearing. You may be deaf in one or both ears. You also may have hearing loss that occurs suddenly or gets worse over time.

Deafness is defined as being unable to hear sounds that are quieter than 81 decibels. By comparison, a normal conversation is around 60 decibels.

Babies and Children

Children who are deaf may not know they have hearing loss. Signs that your child may have hearing loss include:

• Lack of startling, reaction, or attention to sounds
• Language delay
• Speech problems and word mispronunciation
• Behavioral issues 
• Problems with school
• Listening to the TV or radio at a volume that’s too high

Adults

Adults typically notice that their hearing is not as good as it used to be. The sound may be muffled or distorted. You may also hear ringing or buzzing. You may also feel vertigo, like the room is moving even though you are still.

A diagnosis may require several different types of hearing tests given by an audiologist (a hearing specialist) or a healthcare provider like an ear, nose, and throat (ENT) specialist. These tests may include:

• Auditory brainstem response (ABR) or brainstem auditory evoked response (BAER) tests: These tests check to see if your brain responds to sound. They don’t need behavioral responses, so these tests can be performed during sleep if needed.
• Otoacoustic emissions (OAE) test: This test checks your inner ear’s function and response to sound. It can also be performed while you (or your child) sleep.
• Audiometry evaluation: This series of assessments measures your ability to hear various sounds, pitches, and volumes.
• Behavioral audiometry evaluation: This exam tests for the function of all parts of the ear. It requires behavior responses and must be done while you’re awake.

Newborns are usually given a hearing test in the hospital after birth. For older children and adults, your audiologist or healthcare provider will take a detailed history, including family history, a timeline of your hearing loss, and any potential noise exposure.

They will also check your ears for infections, visible damage to the different parts of your ear, and for any fluid or other blockages in your ears. In some cases, imaging of your ears may be taken. 

Most causes of deafness are permanent. For most people, the goal of treating hearing loss is to help improve residual hearing through assistive technologies or to learn how to communicate differently.

Assistive Technology

Common assistive technologies used to improve hearing include:

• Hearing aids: These devices are often worn over your ear and amplify the sound you hear. Hearing aids are often used for conductive hearing loss.
• Cochlear implant: For deafness caused by problems in the inner ear, cochlear implants can send sound signals directly from the outside of the ear to the auditory nerve.
• Auditory brainstem implant: If you can’t use a cochlear implant, an auditory brainstem implant may be used to send sound signals directly to your brain.
• Bone-anchored hearing device (BAHA): This hearing aid sends sound vibrations directly to your inner ear through your bone, bypassing your outer and middle ear. They’re designed to help if you have certain types of hearing loss, such as conductive or mixed hearing loss, or if you have hearing loss in only one ear (single-sided deafness).
• Other technologies: Other options include text messaging, video calling, flashing and vibrating alarms instead of sound-based alarms, and real-time captioning software for phones and TVs.

Deaf Communication 

Some Deaf people communicate using a visual language called sign language. American Sign Language (ASL) is a completely independent language from English, including its own grammar and sentence structure. It relies on using your hands and facial expressions to communicate. 

Sign language is not the same worldwide. There are many different forms of sign language, like there are different spoken languages. 

Some Deaf people can also learn to read speech (lip reading) to help them understand what hearing people are saying. They may also learn to speak a spoken language to communicate with the hearing community. This is typically easier if they were previously able to hear speech.

Not all deafness can be prevented, but you can help reduce the chance of hearing loss. Here are some suggestions:

• Wear proper ear protection in loud areas, such as while mowing the lawn or going to a concert or sporting event
• Treat ear infections promptly
• Receive recommended vaccines before becoming pregnant
• Avoiding chemicals or products that can harm a fetus during pregnancy

If you believe you or your child’s hearing may be worsening, it’s important to speak with a healthcare professional or audiologist for guidance on prevention. 

Most hearing loss is related to age. As you get older, the different parts of your ear may no longer work as well as they once did. Other deafness may be related to genetic causes or other health conditions. These conditions include:

• Down syndrome: A genetic developmental disorder that can cause hearing loss
• Usher syndrome: A genetic disorder that can cause both deafness and blindness
• Chronic ear infection: A health condition that can cause deafness if not treated
• Otosclerosis: Hardening and remodeling of bone in your ear that can cause conductive hearing loss
• Meniere’s disease: An inner ear disorder that can cause vertigo, ringing in the ears, and hearing loss
• Pendred syndrome: A genetic disorder that can cause hearing loss in children 

Deafness is a disability for which you can receive benefits from the Social Security Administration (SSA). The Americans with Disabilities Act (ADA) requires schools and workplaces to ensure reasonable accommodations are available for you to complete your schooling or work. Requesting a sign language interpreter is one example of an accommodation.

Schools work with parents and students on individualized educational plans (IEPs) to ensure equal access and opportunity in school. In some states, public and private deaf schools are also available. 

Many Deaf people do not consider deafness a negative quality. Deaf people perceive the world differently and can be a part of the diverse Deaf community and its culture.