In recent news, it was revealed that hearing loss in children and young adults is on the rise. In 2005/2006, a national health and nutrition survey revealed 1 in 5 children ages 12 to 19 have hearing loss. This reflects a 30% increase since surveys in 1988 and 1994! Children who are exposed to harmful noise over time are at risk to develop hearing loss. Examples of harmful noise can be loud music listening over long periods of time, exposure to power tools, sports arenas, fireworks, etc. Little is known about how "young" ears manage noise compared with "adult" ears. It's important to teach children about the effects of noise to prevent permanent noise-induced hearing loss.
Dangerous Decibels® is a public health partnership for the prevention of noise-induced hearing loss. Its mission is to significantly reduce the prevalence of noise-induced hearing loss and tinnitus (ringing in the ear) through exhibits, educational outreach, and research. Camino ENT supports this mission by offering the knowledge of the Dangerous Decibels® program to its patients in order to protect hearing and improve quality of life.
Our audiologist, Dr. Jennifer Tucker, is a certified Dangerous Decibels Educator and is available to speak to children, young adults, and parent groups. The Dangerous Decibels interactive program is approximately 50 minutes and is designed to raise awareness about the risks associated with exposure to loud noises. Please contact the office or email her directly at dr.tucker@caminoent.com if you are interested in learning more about how this program may benefit your school or group.
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How does human hearing work?
- Sound waves enter the outer ear (pinna and ear canal). The outer ear (auricle or pinna), collects more of a sound wave than a simple hole in the side of one’s head would. Some animals have larger ears that function like ear cones. Some animals can also turn their ears, to listen more effectively to sounds from particular directions.
- The outer ear directs the sound via the ear canal to the ear drum (tympanic membrane) of the middle ear.
- The middle ear consists of the ear drum and the three middle-ear bones (the ossicles, consisting of the hammer or malleus, anvil or incus, and the stirrup or stapes. (These are the smallest bones in the body.)
- The middle ear transforms sound waves into mechanical energy (movements of the middle ear bones), conducting sound to the inner ear.
- The inner ear (cochlea) contains microscopic cells (“hair cells”) that are specialized to convert mechanical energy into electrochemical energy. These are approximately 10 – 15 microns wide – Tiny.
- These hair cells possess tiny finger-like projections, called stereocilia, at their tops. The stereocilia rock back and forth when sound waves reach the inner ear.
- The electrochemical activity of the hair cells activates nerves in the inner ear that, in turn, transmit the sound-induced activity to the brain.
- The brain interprets the incoming neural activity as “I hear something”.
Another way to visualize this process is as a sort of relay race. The vibrations of an object, such as a drum or piano, create sound waves. These sound waves are passed from one air molecule to another until they pass through the outer ear and are ‘handed off’ to the mechanical system of the middle ear. A portion of the middle ear relays the sound to the fluid of the middle ear where the pressure wave causes a membrane (the basilar membrane) to move up and down. This membrane movement in turn stimulates or relays the message, to the hair cells (stereocilia) of the inner ear. The hair cells convert the wave to electro-chemical energy and it is passed to the hearing (auditory) nerve, which relays it to the brain.
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What is Noise-Induced Hearing Loss?
What is Noise-Induced Hearing Loss?We live in an increasingly noisy world. Just as the eye’s sensitivity to light makes it vulnerable to damage from too much light, the ear’s special sensitivity to sound makes it vulnerable to damage from loud sounds, referred to as Noise-Induced Hearing Loss (NIHL). The structures of the ear are tiny and delicate, and can simply be overwhelmed by the effect of loud sound. The louder a sound is, the less time is required to produce damage to hearing. Just as exposure to bright sun for too long can cause sunburn and damage your skin, exposure to intense noise can damage the hair cells in your inner ear, especially if the noise goes on for very long. Unfortunately, the stereocilia of the hair cells of the inner ear do not regenerate, as the skin will.
The delicate hairs at the base of the cochlea are exposed to all sounds and are very susceptible to damage. Because these first hair cells are sensitive to high frequency sounds, higher frequencies hearing is usually the first lost when someone acquires Noise Induced Hearing Loss. So NIHL does not just make everything seem quieter – it actually changes the complex mixture of sound frequencies that the person is able to hear (high frequencies become more difficult or impossible to hear). Speech, for example, is composed of a complex mixture of sound frequencies. The result of changing the sound frequencies that we can hear is to make speech sound “mushy” and much harder to understand particularly when there is background noise. Often, people with Noise Induced Hearing Loss think everyone else is mumbling (when it is really their own hearing that is down). When the mix is altered due to such selective hearing loss, one’s ability to understand speech is impaired, and simply “turning up the volume” with a hearing aid does not fully restore hearing capability. Another unwanted result of the loss of certain sound frequencies is distortion of music. Music may sound distorted, tinny, or “harsh”. Noise-Induced Hearing Loss can cause people to lose their ability to enjoy music. Although they can still hear the music, it no longer sounds good to them.
NIHL often results in tinnitus (ringing or other noises in your ears or head) – no one else can hear these sounds, they are heard only by the person who has undergone noise damage. Tinnitus may become permanent if noise damage is very severe or if the noise exposures are repeated frequently. About 12 million Americans experience permanent, severe tinnitus that often interferes with sleeping and causes other problems in daily life.
The fact that Noise Induced Hearing Loss is often accompanied by tinnitus means that the person has two problems, not just one. Not only do they have trouble hearing what they want to hear, but they hear something they don’t want to hear.
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How does the decibel system work?
How does the decibel system work?
0 decibels represents the softest sound we can hear, the threshold of hearing. An increase of 10 decibels represents a little more than a 3-fold increase (about 3.16) in the air pressure change created by the sound wave. A 20 decibel increase is more than a 3 times 3 increase in sound pressure (about 10 times greater). And a 30 decibel increase is an increase in sound pressure of more than 3 times 3 times 3 (3.16 raised to the third power or 3.16 cubed). In other words, a 40 decibel sound creates sound pressure levels that are more than 30 times as great as a 10 decibel sound. The threshold of pain for the average human ear is 120 decibels. This represents a pressure change over 991,000 times greater than that experienced by the ear when exposed to a 0 decibel sound!
Noise is not the only cause of hearing loss, but it is the most common cause in America (and in other industrialized nations). Loud noises (above 85 dB) can hurt your ears by damaging the sensitive hair cells of the inner ear. It makes no difference whether you like the loud sounds or not – if they are 85 dB and over, they can begin to damage hair cells in your inner ear.
The ability of a normal, healthy human ear to hear spans an enormous range. Because of this, the scale for measuring sound must also span an enormous range yet still be easy and compact to write. This is why the decibel scale is related logarithmically to the huge range of pressure amplitudes that the ear is subjected to. This makes sense because research indicates that humans have evolved a logarithmic response to sound. This helps us to compress the huge range of hearing so that our response to variations in loud sounds is similar to the response to variations in weak sounds. The pressure change experienced by the ear when subjected to a 120 decibel sound (Caution! This is the pain threshold for the average human ear!) is about one million times greater than the pressure change created by the softest sound we can hear, defined as 0 decibels. It is easier and takes less room to write 0 dB or 120 dB than a number followed by six zeroes!
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What is noise pollution?
Noise is defined as “unwanted sound” and it is America’s most widespread nuisance. It is not a new problem. In the first century BC, Caesar banned chariots in Rome to cut down the deafening noise of chariot wheels on stone roads. Throughout the ages people have complained that they can’t “hear themselves think” due to noise. In America, some people talk of “moving to the country” to get away from the noise of the city. Noise presents a real danger to people’s hearing and general health. In addition to the damage noise can cause to our ability to hear, noise can produce other physical and psychological stress. Although we may seem to become accustomed to noise, our bodies still respond and our hearing capability gradually diminishes. Noise exposure has been linked to:
- permanent hearing damage resulting in reduced ability to communicate
- increased adrenaline, high blood pressure and faster heart rate
- heart and circulatory disease
- overall stress on the body
- problems with fetal development and low birth weight
- interference with the development of language skills
- interference with conversation and social interaction
- diminished work efficiency
- diminished quantity and quality of sleep
- increase in antisocial behavior, extreme emotions and behavior
- accidents, due to overall stress and due to obscuring audible alarms
Despite our knowledge that noise is damaging to our health, the noise levels in our environments continue to rise. The Acoustical Society of America indicates that since 1950 the volume of noise in daily life has doubled every ten years.
Unfortunately, the damage that sound can inflict on our ears does not depend on whether we like it or not. A concert can be just as damaging as noise from firearms or sirens or noisy engines. Also, growing accustomed to loud noise does not diminish its ability to damage our hearing or to cause other physiologic effects.
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What are some signs of dangerous decibels?
What are some signs of dangerous decibels?- Do you often have to shout for people to hear you?
- After being around loud sound, did you ever have a ringing or other noises in your ears or head (tinnitus)?
- Does music sound a little strange after you listen for a while?
- After being near loud sound, does it sound like people are talking to you through a pillow?
- After being near loud sound, do your ears sometimes feel “full” or “stopped up”?
- When you are listening to stereo headphones or a Walkman, can a person standing next to you hear it too?
If you answered YES to any of these questions, you have been exposed to damaging sound levels.
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How YOU can protect your hearing:
How YOU can protect your hearing:Doctors cannot fix ears that have been damaged by loud sound. So it is very important to protect your ears. It is not difficult to avoid most exposure to damaging sounds. There are three main methods for making sure your hair cells don’t undergo noise-induced damage.
- Turn it Down! (Stereos, iPods, “Boom Boxes”, other heavy sources)
- Protect your ears! (Carry and use ear plugs when going to an amplified concert, when using power tools, when around motorcycles or other noisy vehicles like jet skis and snowmobiles)
- Walk Away! (This is what you do if you can’t do either #1 or #2 above). It’s easy to demonstrate how increasing the distance between you and the sound source can reduce the amount of sound you are exposed to.
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