Majority of people begin experiencing a decline in their hearing as they get older. If they are healthy and were not exposed to noise, the symptoms of hearing loss may begin to show after the age of 60. However, excessive noise exposure is dangerous and can result in permanent hearing loss at an early age. For example, by age 25 the average carpenter has "50-year old" ears! That is, by age 25, the average carpenter has the same hearing as someone who is 50 years old and has worked in a quiet job.
You cannot train your ears to accept loud noises. Once the delicate inner structure of ear is damaged by noise, no medical or surgical treatment will restore your hearing to “normal.” Even hearing aids are only able to improve your hearing.
How does “normal” hearing work?
Hearing depends on a series of events that change sound waves in the air into electrical signals. Our auditory nerve then carries these signals to the brain through a complex series of steps.
- The three parts of the ear anatomy are the outer ear, the middle ear and the inner ear. The inner ear is also called the cochlea (‘Cochlea’ means ‘snail’ in Latin and gets its name from its distinctive coiled shape).
- Sound waves enter the outer ear, travel down the ear canal and make the ear drum vibrate.
- This action moves the tiny chain of bones in the middle ear. The last bone in this chain ‘knocks’ on the membrane window of the cochlea and makes the fluid in the cochlea move.
- The fluid movement then triggers a response in the hearing nerve located in the inner ear. Our brain interprets the nerve impulses as sounds.
How does noise damage hearing?
Since the nerve endings in the inner ear send impulses to the brain, which are then interpreted as sound, a decrease in the number of nerve endings will impact a person’s ability to hear. Noise can destroy the nerve endings in the inner ear. When the nerve endings are killed, this results in sensorineural hearing loss or nerve deafness. Hearing loss will grow progressively worse as the number of destroyed nerve ends grows. At this point, the hearing loss is permanent because the damaged nerve endings cannot be restored.
What does it mean to be hard of hearing?
“Hard of hearing” denotes a mild to severe hearing deficit. People who are hard of hearing may benefit from the use of hearing aids or other assistive listening devices. However, it should be noted that hearing aids can only improve a person’s hearing, they cannot restore it to “normal.”
What is noise-induced hearing loss (NIHL)?
As we go about our day, sound is all around us, from We experience sounds everyday televisions, lawnmowers, household appliances, construction equipment and traffic. Normally, these sounds are at safe levels that don’t damage our hearing. But sounds can be harmful when they are too loud or both loud and long-lasting. In addition, noise exposure is cumulative. So the noise at home, at work or at play must be counted in the total exposure during the day. The damage to the nerve endings of the inner ear as a result of all the noise exposure can cause noise-induced hearing loss (NIHL).
NIHL can be immediate or it can take a long time to be noticeable. It can be temporary or permanent, and it can affect one ear or both ears. The good news is noise-induced hearing loss is something you can prevent by using hearing protection devices and avoiding unprotected exposure to dangerous noise levels.
Who should wear hearing protectors?
If you must work in an excessively noisy environment, you should wear protectors. You should also wear them when using power tools, noisy yard equipment, or firearms, or riding a motorcycle or snowmobile.
Can noise affect more than my hearing?
Loud noise exposure can also cause tinnitus — a ringing, buzzing, or roaring in the ears or head. For some, the symptoms of tinnitus may subside over time. But others can experience tinnitus constantly or sporadically throughout a their lifetime.. Hearing loss and tinnitus can occur in one or both ears.
What is a decibel and how does it impact hearing?
A decibel (dB) is a unit that measures the intensity or loudness of sound.
Sounds of less than 75 decibels, even after long exposure, are unlikely to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.
Here are the average decibel ratings of some familiar sounds:
- Whisper, quiet library
- The humming of a refrigerator
- Normal conversation
- Noise from heavy city traffic
- An MP3 player at maximum volume
- Firecrackers and firearms
How can I tell if the noise is too loud?
While people have different tolerance levels to noise, two simple rules can help determining when noise is dangerous to your health:
- First, if you have to raise your voice to talk to someone who is an arm's length away, then the noise is likely to be hazardous.
- Second, if your ears are ringing or sounds seem dull or flat after leaving a noisy place, then you probably were exposed to hazardous noise.
The impact of noise adds up over a lifetime. If you are exposed to loud sounds on a regular basis, your risk for permanent damage increases over time. Even a single but long-lasting loud event can cause damage. Limit your exposure to sounds at or above 100 decibels to no more than 15 minutes, and limit sounds that are at or above 110 decibels to no more than 1 minute.
What are the warning signs that your workplace may be too noisy?
Noise may be a problem in your workplace if:
- You hear ringing or humming in your ears when you leave work.
- You have to shout to be heard by a coworker an arm's length away.
- You experience temporary hearing loss when leaving work.
What are my employer’s responsibilities regarding occupational noise exposure?
The Occupational Safety and Health Administration (OSHA) sets standards and legal limits on noise exposure in the workplace.
In 1981, OSHA implemented new requirements to protect all workers in general industry (e.g. the manufacturing and the service sectors) for employers to implement a Hearing Conservation Program where workers are exposed to a time weighted average noise level of 85 dB A or higher over an 8 hour work shift.
Hearing Conservation Programs require employers to measure noise levels, provide free annual hearing exams and free hearing protection, provide training, and conduct evaluations of the adequacy of the hearing protectors in use unless changes to tools, equipment and schedules are made so that they are less noisy and worker exposure to noise is less than the 85 dB A.
Workers should check with their employers for specific information.
What are hearing protectors? What types are available?
In order to decrease the intensity of sounds reaching the ear drum, proper hearing protection devices should be worn. Simply stuffing your ears with cotton balls or tissue paper will not offer sufficient protection since they only reduce noise by approximately 7 decibels. There are many hearing protection options available and choices vary depending on whether you’re mowing the lawn or working in a machine factory. Here are some common options:
Expandable foam plugs
These plugs are made of a formable material designed to expand and conform to the shape of each person's ear canal. A few manufacturers now offer a small size expandable plug.
Pre-molded, reusable plugs
Pre-molded plugs are made from silicone, plastic or rubber and are manufactured as either “one-size-fits-most” or are available in several sizes. Many pre-molded plugs are available in sizes for small, medium or large ear canals, Keep in mind you may need a different size plug for each ear.
Canal caps often resemble earplugs on a flexible plastic or metal band. The earplug tips of a canal cap may be a formable or pre-molded material. Some have headbands that can be worn over the head.
Earmuffs come in many models designed to fit most people. They work to block out noise by completely covering the outer ear.
Still, the best hearing protector is the one that is comfortable and convenient and that you will wear every time you are in an environment with hazardous noise.
Do hearing protectors work?
Properly fitted earplugs or muffs can reduce noise 15 to 30 decibels. When measuring the effectiveness of hearing protectors, studies have shown that one-half of the workers wearing hearing protectors receive one-half or less of the noise reduction potential of their protectors because these devices are:
- not worn continuously while in noise, or
- because they do not fit properly.
Even if ear protectors are worn continuously they do little good if there is an incomplete air seal between the hearing protector and the skin. A useful sign that the hearing protectors are properly positioned and properly fit inside the ear canal is when the wearer hears their own voice as louder and deeper.
Do hearing protectors prevent a person from communicating with others?
People with normal hearing will not have trouble understanding regular conversation while wearing hearing protection. If you use the sunglasses analogy, whereby sunglasses help vision in very bright light, hearing protectors help enhance speech understanding in very noisy places. However, people with compromised hearing or problems understanding speech, will have difficulty understanding normal conversation while wearing hearing protection devices.
What if my hearing is already damaged? How can I tell if I have hearing loss?
The progression of hearing loss is usually painless and gradual; you might not even notice it. But there is cause for concern if you are experiencing any of these symptoms:
- trouble understanding what people say they may seem to be mumbling, especially when you are in a noisy place such as in a crowd or at a party.
- difficulty hearing high pitched sounds like the voices of women and children
- difficulty in detecting differences between certain words that sound alike, especially words that contain S, F, SH, CH, H, or soft C sounds
- ringing or other sound in your ear (called tinnitus)
If you suspect hearing loss, consult a physician with special training in ear care and hearing disorders, called an otolaryngologist or otologist. This doctor can diagnose your hearing problem and send for additional diagnostic exams, including hearing tests.