Hearing loss is sometimes considered simply a sign of aging. But what we do in our lives can determine how soon, quickly, and how much hearing we will lose. Hearing loss is considered the third most common health problem in the United States.
The Basics: How Do We Hear?
Our ears have three major areas: the outer ear, the middle ear, and the inner ear. Hearing is a result of sound waves from the air being changed into electrical signals that nerves send to the brain to interpret as sounds.
First sound waves enter the outer ear and move through the ear canal. The eardrum, at the end of the ear canal, vibrates from the sound waves. These vibrations are sent to three tiny bones in the middle ear: malleus, incus, and stapes. These bones manipulate the sound vibrations for the cochlea, in the inner ear.
The cochlea is split into an upper and lower area by the basilar membrane. The vibrations make the fluid in the cochlea move along the basilar membrane and hair cells that sit on top of it ripple from the moving fluid. Different hair cells detect different sounds - those near the end of the cochlea detect high-pitched sounds, and those closer to the center of the cochlea detect low-pitched noises.
The stimulation of the hair cells cause stereocilia (sitting on top of the hair cells) to bend and open up, allowing chemicals to move into the cells which makes an electrical signal. Auditory nerves bring this signal to the brain, which interprets the sound and makes us understand what it is.
What We Hear
Sounds are rated on a scale of decibels. Human ears can hear 0 - 140 decibels (but keep in mind 0 doesn’t mean no sound - it means we cannot hear it, and even though we can hear 140 decibels, it is so loud it can cause permanent damage to our ears).
- A painful sound would be a gun going off and results in permanent hearing loss - 140 decibels
- A chainsaw or a concert is considered extremely loud at 110 decibels
- A very loud sound is a blow-dryer, blender, or food processor at 80-90 decibels - this is a level of sound that the National Institute for Occupational Safety and Health recommends workers limit their exposure to as much as possible
- A loud sound, which is okay to hear for a full day, is busy traffic - 70 decibels
- A moderate sound can be heard for over a day, and is something such as a normal conversation or a dishwasher at 60 decibels
- A faint sound is a whisper, which is 30 decibels
If you have to raise your voice to be heard, can’t hear the person standing next to you, or after leaving the noisy environment feel like sounds are muffled, it is a dangerous noise level.
Hearing Loss: Disease
There are some disorders and diseases that develop that damage the ears and cause hearing loss. Otosclerosis affects those three tiny bones in the middle ear, which means they don’t help with hearing as effectively. This problem can often be surgically treated.
Ménière's disease causes problems to the inner ear and results in hearing loss, dizziness, tinnitus (ringing in the ear), and sensitivity to loud noises. A doctor and audiologist help manage this disease, but the hearing loss can become permanent over time.
Ear infections could hurt hearing, along with abnormal bone growth or tumors when in the outer or middle ear. Diseases such as heart disease, high blood pressure, and diabetes can up risk for hearing loss due to interference with the ears’ blood supply.
Sudden hearing loss, which means a loss of 30 decibels or more in hearing ability over hours or days, can happen abruptly, typically in one ear. A normal conversation is 60 decibels, so sudden hearing loss would make it more difficult to hear everything. The cause is only figured out about 10-15% of the time.
Hearing Loss: Trauma and Noise
Trauma to the ear can include many things. It could be injury, such as a skull fracture or a punctured eardrum (don’t put Q-tips inside your ear to clean out wax!). It could also just be the result of particularly loud noise that damaged the hair cells in your inner ear - once these cells are damaged, they don’t repair themselves so the electrical signals to the brain don’t work correctly.
If you go to a loud concert and find that sounds are muffled after or there’s a ringing in your ears, it means there has been some damage in your ears. This can sometimes recover after being away from the noise, but over time hearing loss can become permanent if you continue to expose yourself to dangerous noise levels.
Do you listen to music in headphones or earbuds? It’s estimated that 15-25% of people listen to their music too loudly. You can listen to music at about 80% of the maximum volume for 90 minutes at a time or less, and it won’t result in ear damage. Noise-cancelling headphones can help people listen to softer music since they aren’t competing with other noises to properly hear the music.
Hearing loss as a result of exposure to noise that is too loud causes permanent hearing loss over time. Ears do not “get used” to certain levels of noise, and instead the hair cells in ears get irreparably damaged.
Hearing Loss: Age
Losing hearing as we age is known as age-related hearing loss, and is a very common condition for aging adults - one-third of ages 65-74 in the US have hearing loss, and half of people over age 75 have hearing difficulty. Typically age-related hearing loss occurs in both ears and is very gradual, so overtime many people don’t actually realize their hearing has diminished. Hearing loss for most older adults is related to both age and noise-induced hearing loss.
There are many causes for this loss of hearing, but it mainly results from changes within the inner ear due to age. Changes in the middle ear or along nerve pathways from the ear to the brain can also cause hearing loss with age. The eardrum and the three bones in the middle ear may have reduced function that disrupt hearing.
The real question is: can age-related hearing loss be prevented? Well, no one really knows yet how to prevent it. All you can do is avoid getting noise-induced hearing loss by being careful around high levels of sound by using earplugs or getting out of noisy environments.
Do You Have Difficulty Hearing?
Do you struggle to hear when others talk and feel frustrated about it? Do you have trouble hearing in a movie theater, while watching TV, or listening to the radio? Do you frequently mishear things and get corrected? Do you have trouble hearing people speaking in environments such as restaurants?
All of these things indicate hearing loss. First, anyone suspecting hearing loss should visit their primary care physician to get referred to an expert, such as an otolaryngologist (also known as ENT - specialist for diseases of the ear, nose, throat, and neck), audiologist (measuring degree and determining type of hearing loss), or hearing aid specialist.
Treatment will be determined based on the type and severity of hearing loss:
- Hearing aids: electronic instruments that make sounds louder
- Cochlear implants: surgically implanted electronic devices that give a sense of sound to those who are deaf or profoundly hard-of-hearing
- Bone anchored hearing systems: use bone conduction to help the body’s ability to transfer sound - a sound processor registers sound, turns it into vibrations, then sends the vibrations through your skull bone to the inner ear
- Assistive listening devices: amplifying devices used for cell phones, telephones, theaters, and auditoriums
- Lip reading: special trainers can teach how to follow conversational speech without needing to hear
EMS and Hearing Loss
As a first responder, you may encounter many older patients who are experiencing hearing loss - whether they know it or not. If they struggle to understand you, or get angry that they mishear you, just speak slower and try to enunciate. Be patient and repeat yourself as needed.
Sources and More Information
American Speech-Language-Hearing Association, “Causes of hearing loss in adults” http://www.asha.org/public/hearing/Causes-of-Hearing-Loss-in-Adults/
Alpine Hearing Protection, “5 Sound Levels in Decibels” https://www.alpinehearingprotection.com/wiki/5-sound-levels-in-decibels/
Huffington Post, “How to listen to loud music on headphones without hurting your ears” by Kerry Flynn, http://www.huffingtonpost.com/2014/11/24/loud-music-headphones_n_6174340.html
Mayo Clinic, “Hearing Loss” http://www.mayoclinic.org/diseases-conditions/hearing-loss/basics/causes/con-20027684
NIH: National Institute on Deafness and Other Communication Disorders (NIDCD), “How Do We Hear?” https://www.nidcd.nih.gov/health/how-do-we-hear
“Age-Related Hearing Loss” https://www.nidcd.nih.gov/health/age-related-hearing-loss
WebMD, “Hearing Loss” http://www.webmd.com/a-to-z-guides/hearing-loss-causes-symptoms-treatment#1
Jenny Ewen, BA, EMT