What is noise-induced hearing loss?
Every day, we experience sound in our environment, such as the sounds from television and radio, household appliances, 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, even for a brief time, or when they are both loud and long-lasting. These sounds can damage sensitive structures in the inner ear and 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. Even if you can’t tell that you are damaging your hearing, you could have trouble hearing in the future, such as not being able to understand other people when they talk, especially on the phone or in a noisy room. Regardless of how it might affect you, one thing is certain: noise-induced hearing loss is something you can prevent.
Who is affected by NIHL?
Exposure to harmful noise can happen at any age. People of all ages, including children, teens, young adults, and older people, can develop NIHL.
What causes NIHL?
NIHL can be caused by a one-time exposure to an intense “impulse” sound, such as an explosion, or by continuous exposure to loud sounds over an extended period of time, such as noise generated in a woodworking shop.
Recreational activities that can put you at risk for NIHL include target shooting and hunting, snowmobile riding, listening to MP3 players at high volume through earbuds or headphones, playing in a band, and attending loud concerts. Harmful noises at home may come from sources including lawnmowers, leaf blowers, and woodworking tools.
Sound is measured in units called decibels. 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:
The humming of a refrigerator 45 decibels
Normal conversation 60 decibels
Noise from heavy city traffic 85 decibels
Motorcycles 95 decibels
An MP3 player at maximum volume 105 decibels
Siren 120 decibels
Firecrackers and guns 150 decibels
Your distance from the source of the sound and the length of time you are exposed to the sound are also important factors in protecting your hearing. The amount of sound a gunshot puts out depends on amongst other things, how close the shooter’s ear is to the source of the sound of the shooting instrument. For example, a .22 caliber round will cause more ear trauma when fired from a rifle than from a pistol. Why? Because when fired from the rifle, the boom is closer to the shooter’s ear, therefore capable of doing more damage.
So, given these numbers and the differences in shooting sports (rifle, pistol, cartridge, shell, etc.), we can comfortably say that, if you’re the shooter, you’re being exposed to more than 100 dB’s each time the trigger is pulled.
And consider other shooting sports enthusiasts. This involves more than a deer hunter who gets off 10 shots in a season. There are target shooters who use rifles and pistols often in enclosed spaces. 12-gauge shotguns are the weapon of choice for skeet and trap shooters. Those shells produce damaging concussive waves of sound which at the very least can cause ringing in the ears (tinnitus) for hours especially when you’re playing as part of a foursome. For example, 25 clay pigeons in a round of skeet times four shooters in the space of one-half hour, exposes the ears to 100 concussions.
A good rule of thumb is to avoid noises that are too loud, too close, or last too long.
How can noise damage our hearing?
Credit: NIH Medical Arts
To understand how loud noises can damage our hearing, we have to understand how we hear. 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.
- Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum.
- The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes.
- The bones in the middle ear couple the sound vibrations from the air to fluid vibrations in the cochlea of the inner ear, which is shaped like a snail and filled with fluid. An elastic partition runs from the beginning to the end of the cochlea, splitting it into an upper and lower part. This partition is called the basilar membrane because it serves as the base, or ground floor, on which key hearing structures sit.
- Once the vibrations cause the fluid inside the cochlea to ripple, a traveling wave forms along the basilar membrane. Hair cells—sensory cells sitting on top of the basilar membrane—ride the wave.
- As the hair cells move up and down, microscopic hair-like projections (known as stereocilia) that perch on top of the hair cells bump against an overlying structure and bend. Bending causes pore-like channels, which are at the tips of the stereocilia, to open up. When that happens, chemicals rush into the cell, creating an electrical signal.
- The auditory nerve carries this electrical signal to the brain, which translates it into a sound that we recognize and understand.
Stereocilia perch atop sensory hair cells in the inner ear. Credit: Yoshiyuki Kawashima
Most NIHL is caused by the damage and eventual death of these hair cells. Unlike bird and amphibian hair cells, human hair cells don’t grow back. They are gone for good.
What are the effects and signs of NIHL?
When you are exposed to loud noise over a long period of time, you may slowly start to lose your hearing. Because the damage from noise exposure is usually gradual, you might not notice it, or you might ignore the signs of hearing loss until they become more pronounced. Over time, sounds may become distorted or muffled, and you might find it difficult to understand other people when they talk or have to turn up the volume on the television. The damage from NIHL, combined with aging, can lead to hearing loss severe enough that you need hearing aids to magnify the sounds around you to help you hear, communicate, and participate more fully in daily activities.
NIHL can also be caused by extremely loud bursts of sound, such as gunshots or explosions, which can rupture the eardrum or damage the bones in the middle ear. This kind of NIHL can be immediate and permanent.
Loud noise exposure can also cause tinnitus—a ringing, buzzing, or roaring in the ears or head. Tinnitus may subside over time, but can sometimes continue constantly or occasionally throughout a person’s life. Hearing loss and tinnitus can occur in one or both ears.
Sometimes exposure to impulse or continuous loud noise causes a temporary hearing loss that disappears 16 to 48 hours later. Recent research suggests, however, that although the loss of hearing seems to disappear, there may be residual long-term damage to your hearing.
Can NIHL be prevented?
NIHL is the only type of hearing loss that is completely preventable. If you understand the hazards of noise and how to practice good hearing health, you can protect your hearing for life. Here’s how:
- Know which noises can cause damage (those at or above 85 decibels).
- Wear earplugs or other protective devices when involved in a loud activity to protect the delicate inner ear mechanism using one of many options available. Some of these choices are over-the-ear cups, earmuffs, generic ear plugs or custom made ear plugs. Activity-specific earplugs and earmuffs are available at hardware and sporting goods stores. The choice of which method of ear protection is worn depends on the frequency of exposure to gun and rifle shot and personal preferences for wearing comfort.
- Everyonewithin ear shot should wear some kind of ear protection even if just a weekend spectator. Expect loud bursts of noise and protect yourself using some form of hearing protection.
- If you can’t reduce the noise or protect yourself from it, move away from it.
- Be alert to hazardous noises in the environment.
- Protect the ears of children who are too young to protect their own.
- Make family, friends, and colleagues aware of the hazards of noise.
- Have your hearing tested if you think you might have hearing loss.
What research is being done on NIHL?
The National Institute on Deafness and Other Communication Disorders (NIDCD) supports research on the causes, diagnosis, treatment, and prevention of hearing loss. NIDCD-supported researchers have helped to identify some of the many genes important for hair-cell development and function and are using this knowledge to explore new treatments for hearing loss.
Researchers are also looking at the protective properties of supporting cells in the inner ear, which appear to be capable of lessening the damage to sensory hair cells upon exposure to noise.
www.nidcd.nih.gov NIDCD Fact Sheet Noise-Induced Hearing Loss
www.heathyhearing.com Shooting Sports and Hearing Loss
As with the eye, the ear’s performance is affected by ageing. However, bad vision gradually makes reading harder as the letters get smaller as in the chart below but hearing loss is different. In hearing impairment some sounds in a word may be heard clearly but other sounds particularly consonants may not, causing overall speech to sound ‘muffled’ or unclear. Hearing loss can make certain syllables and sounds harder to hear. For example, high-pitched consonants like f, s, th, c, st and t are easily drowned out by louder, low-pitched vowels like a, o and u. This results in a person with hearing loss complaining that they can hear others are talking, but not what they are saying. They can hear but do not always understand particularly in noise. Listening with an untreated hearing loss can be compared to Swiss cheese; there are ‘holes’ in the conversation.
HEARING LOSS VS VISUAL IMPAIRMENT
Hearing loss usually begins unnoticed. On average, people with hearing loss wait almost 10 years before they do something about it. Too few people make a timely decision to take active steps to recover their hearing and increase their quality of life.
Studies show that as people lose their hearing, they are more prone to depression; they withdraw socially and communicate less with family and friends. This comes as no surprise – after all, you can’t participate in conversation if you can’t hear or understand what’s being said!
Better Hearing Institute encourages people with diabetes to take care of their hearing by following these five healthy habits:
- Get a thorough hearing exam every year and watch for signs of hearing loss. You do it for your eyes. Now do it for your ears. See a hearing healthcare professional every year for a thorough hearing examination. If you notice a change in your ability to hear under certain conditions—like at a restaurant or on a conference call—go sooner. And be sure to share the information with your primary care physician and endocrinologist.
- Keep your blood sugar under control. Just as your heart, eye, and nerve health are affected by your blood sugar levels, your hearing health may be as well. Work with your doctor to monitor your blood sugar and take appropriate medicines as prescribed.
- Maintain a healthy lifestyle. Even for people without diabetes, a healthy lifestyle benefits hearing health. Not smoking, exercising, and maintaining a healthy diet all support your ability to hear. In fact, studies show that smoking and obesity increase the risk of hearing loss, while regular physical activity helps protect against it.
- Use ear protection. Everyone is at risk of noise-induced hearing loss. But using ear protection is one of the best—and simplest—things you can do to preserve your hearing. Carry disposable earplugs with you, especially when you know you’ll be somewhere noisy. Use appropriate ear protection in loud work environments. Keep the volume on smartphones and other electronics low. Limit your use of headphones and ear buds. And get in the habit of quickly plugging your ears with your fingers and walking away if a loud noise takes you by surprise. Most of all, limit your time in noisy environments.
- Use hearing aids, if recommended. Hearing aid technology has advanced radically in recent years. While hearing loss is not reversible, today’s hearing aids can dramatically enhance your ability to hear and engage with others- which can make a tremendous difference in your overall quality of life. They adjust to all kinds of noise environments and pick up sound from all directions. Best of all, they’re wireless. Today’s hearing aids can stream sound directly from your smartphone, home entertainment system, and other electronics directly into the hearing aid itself – at volumes just right for you.
Family of hearing aid batteries.
How long should a person wait after taking the tab off a battery before inserting it into a hearing aid?
We recommend about 1 minute. It’s enough time to let air get into the battery to help activate it. People take the tab off and wait anywhere from five minutes, to a couple hours, to let it sit overnight, but really only about a minute is needed.
Waiting a full minute ensures a good start condition for the battery. People think that waiting a full minute for the battery to power up means they will get longer life from the battery. That’s not really true.
Think about turning on your computer. You have to wait for it to boot up before you start using it. The same thing actually occurs with a hearing aid. A hearing aid has a boot up sequence and it requires a lot of power. So you want to ensure your hearing aid battery has the voltage to power that start up sequence. Allowing the battery to wait for one minute after it’s un-tabbed before inserting it into the aid will ensure it has the voltage it needs to support the startup sequence.
How can I maximize battery life in my hearing aid?
Turning the hearing aids off and opening the battery doors when you’re not using them is the best advice. Always buy fresh batteries, and store them in a cool, dry location. Don’t keep them in your glove compartment, in the refrigerator, on your radiator, or anywhere they’ll be exposed to temperature extremes. Keep them in the original packaging and obviously, don’t remove the tabs until ready to use.
Hearing aid batteries today don’t last as long today as they used to 5 or 10 years ago – why the difference?
It’s due to the innovation in hearing aid technology; today’s hearing aids are essentially mini computers. They require significantly more power than the old analog hearing aids of years past. These computers analyze sound and make decisions and the sound processing is very sophisticated. Processing is measured in MIPS or million instructions per second. The more instructions that occur in that timeframe, the more power is required to run the hearing aid.
What are realistic expectations when it comes to hearing aid battery life, since it varies so much from person to person?
There is a realistic range for battery life, rather than a specific number of days.
Battery life is going to be very individual;
- two people using the same style and make of hearing aid won’t necessarily have the same battery life
- battery life depends on the hearing aids’ settings, what features are active, how many hours a day the hearing aids are used, and the environments that a person is in. Obviously, a person who wears hearing aids for 16 hours a day is not going to have the same battery life as one who only wears hearing aids for 8 hours a day
- technology that communicates between the right and left hearing aids is beneficial but also contributes to slightly higher battery drain
- it’s very common that the batteries in a binaural (worn in each ear) set of hearing aids will last different amounts of time. That’s because if the hearing loss is different between the ears, then the programming between the right and left hearing aid is different. This impacts battery life.
- it’s important to be aware of how the features in the hearing aids may impact battery life. For example, take a week when a person is home and it’s quiet. You may watch television, and have one-on-one conversations with your spouse. Let’s say your hearing aid battery lasts the entire week. Then, the following week you attend a family reunion, have a lot of company, and attend a football game. Your battery life may be five days because of the change in your lifestyle and the demands on the hearing aid signal processing. People may be confused if they expect that their battery will always last a specific number of days, as it really depends on the environments they’re in and the demands on their hearing aid technology
So there are many individual factors to consider.
How can the calendar be used to track battery life?
When a person first gets the hearing aids, their battery life can be tracked on the calendar to get an idea when the batteries may need to be changed. For the first few months, stick the battery tabs on the calendar every time the batteries are replaced. This way a person can get an idea of the average amount of time the batteries will last.
Ask the Expert from an AudiologyOnline interview
Keeping the people you love in the conversation and part of the celebration is one of the most meaningful things you can do this holiday season.
Even when surrounded by loved ones, a friend or family member’s difficulty hearing can make them feel cut off. Too often, people with unaddressed hearing loss withdraw socially and experience sadness—even symptoms of depression—during the holidays.
Don’t let that happen to the people you care about. Instead, lend inspiration and support.
If you’re hosting a holiday party this year, consider these 9 tips to help ensure that your friends and family who may be struggling with untreated hearing loss stay part of the festivities:
- Be attentive: Stay vigilant if you see that a family member or friend is quiet at a holiday dinner or party. Maybe they’re having trouble hearing and need your help in bringing them back into the conversation.
- Turn down the volume: Loud background music or the roar of the TV can make it especially hard to hear at the dinner table. Consider keeping the music and television off during mealtime.
- Keep the room well lit: Providing good lighting will make it easier for those with hearing loss to see facial expressions and the mouths of those speaking. Also, be sure to shade any glare from windows that might make it difficult to see faces.
- Speak clearly: Do your best to speak slowly and at a comfortable volume without mumbling or slurring your words. Project your voice, but don’t shout. It’s best not to chew gum, smoke, or put your hands to your face while speaking. Also avoid Interrupting, which makes it harder to follow a conversation.
- Face the person: Facing the person you are speaking with makes it easier for them to hear the words but also to see your mouth and facial expressions. It’s also a good idea to get their attention before speaking by saying their name or gently touching their hand, arm, or shoulder.
- Rephrase: Often people will repeat themselves if someone didn’t hear them. Instead, consider rephrasing what you said. Oftentimes that makes it easier for the individual with hearing difficulty to follow the conversation because it may be a particular word or sound of speech that they’re having trouble deciphering.
- Stay close: When you’re not sitting around the dinner table, be sure to stay close to those with hearing loss when speaking to them. It is much more difficult to hear someone from across the room and harder to see their mouth and facial expressions.
- Seek them out: Sometimes the best thing you can do for someone who is having difficulty hearing is to seek them out and enjoy a one-on-one conversation in a quiet corner, a quiet room, or during a quiet walk.
- Seat them next to someone who will be a patient advocate: Some people are just good at being aware of others’ needs and empathizing. If someone you love is struggling with hearing loss, try to pair them at the dinner table with someone who will be proactive in making sure they’re following the conversation and patient if they need things repeated or rephrased. Also consider seating the loved one with hearing loss at the head of the table, which can make it easier for them to see the other guests’ faces. Better yet, use a round table.
The intensive listening effort demanded by untreated hearing loss can be extremely stressful.
Experts believe that even if you have just a mild hearing loss that is not being treated, thought and reasoning load increases significantly leading to stress in many if not all social and personal situations. Withdrawal from social situations, a lessened ability to cope and reduced overall psychological health are just some of the conditions associated with unaddressed hearing loss. Along with often feeling stress, people with untreated hearing loss may feel angry, frustrated, anxious, isolated, and depressed.
Even one-on-one situations with loved ones can be very stressful due to frequent misunderstandings, mistakes and even arguments.
When people with hearing loss use hearing aids they often regain emotional stability; have an easier time joining in groups and become more socially engaged; experience a greater sense of safety and independence; feel more in control of their lives; and see a general improvement in their overall quality of life. Many even report improvements in their relationships at home and at work resulting in significant reduction of stress.
Reference: Better Hearing Institute www.BetterHearing.org
Chronic Kidney Disease – CKD
Older adults with moderate chronic kidney disease (CKD) have a higher prevalence of hearing loss than those of the same age without CKD, according to a new report published in the American Journal of Kidney Diseases, the official journal of the National Kidney Foundation.
The link can be explained by structural and functional similarities between tissues in the inner ear and in the kidney. Additionally, toxins that accumulate in kidney failure can damage nerves, including those in the inner ear.
The implication is that the results of clinical hearing assessments may indicate to the medical practitioner the need for investigating kidney function in older adults. Management of CKD may potentially preserve hearing function.
The Association Between Reduced GFR and Hearing Loss: A Cross-sectional Population-Based Study
Eswari Vilayur, MBBS Bamini Gopinath, PhD David C. Harris, MD, PhD George Burlutsky, MApplStat Catherine M. McMahon, PhD Paul Mitchell, MD, PhD
The audiogram pattern correlates strongly with cerebrovascular and peripheral arterial disease and may represent a screening test for those at risk.
New research in the February issue of Atherosclerosis suggests that hearing loss may be an early sign of cardiovascular disease in seemingly healthy middle-aged people. When controlling for age, hypertension, diabetes, smoking, and hyperlipidemia, low-frequency presbycusis (hearing loss) was significantly associated with intracranial vascular pathology such as stroke and transient ischemic attacks. Significant associations were also seen with peripheral vascular disease, coronary artery disease, and a history of myocardial infarction.
David R. Friedland, MD, PhD, Professor and Vice-Chair of Otolaryngology and Communication Sciences at the Medical College of Wisconsin in Milwaukee, explains the cardiovascular-hearing health link: “The inner ear is so sensitive to blood flow that it is possible that abnormalities in the cardiovascular system could be noted here earlier than in other less sensitive parts of the body.”
Patients of any age with low-frequency hearing loss should be regarded as at risk for cardiovascular events, and appropriate intervention should be considered. Interventions targeting atherosclerosis prevention may also help to prevent or delay the onset of hearing impairment.
Keeping track of hearing ability by referring patients for a hearing test may help the physician in the monitoring of cardiovascular health.
Subclinical atherosclerosis and increased risk of hearing impairment Mary E. Fischeremail Carla R. SchubertemailDavid M. Nondahlemail Dayna S. Daltonemail Guan-Hua Huangemail Brendan J. Keatingemail Barbara E.K. Kleinemail Ronald Kleinemail Ted S. Tweedemail Karen J. Cruickshank