by Susan Heckler
What did you say? Can you speak up? How many times a day do you hear those questions and under what circumstances? It seems that more and more people are showing signs of hearing loss. A 1971 federal survey estimated 13.2 million Americans had hearing loss. It is up to 36 million Americans who now report lost hearing.
This used to be an affliction for the elderly, but the baby boomers are not hearing the booms anymore. In this generation and those that followed, noise, not age is the leading cause of hearing loss. Tens of millions of people in the U.S. alone, including 12 percent to 15 percent of school-age children, already have permanent hearing loss caused by everyday noise.
Our ears are very fragile instruments. Sound waves, or an acoustic signal, cause the eardrum (tympanic membrane) to vibrate. Those vibrations are transferred to the cochlea, which is in the inner ear. Fluids then carry them to rows of hair cells. The hair cells stimulate auditory nerve fibers, each of which is attuned to a different frequency. These impulses travel through the auditory nerve to the brain. The brain then interprets them as words, music, or specific sounds. When there is too much sound intensity going through the auditory system, Noise-induced Hearing Loss (NIHL) can occur. In actuality, it is the oxidative death of the hairs cells caused by over stimulation.
Fortunately, this is a preventable hearing disorder. Unfortunately, we didn’t know any of this when we were rocking out at concerts or plugged in to our Walkman. NIHL can happen gradually from repeated overexposure to sounds over a long period of time. It can also happen from a onetime exposure such as an explosion.
NIHL is generally observed to affect a person’s hearing sensitivity in the higher frequencies, especially at 4000 Hz. All the sounds we hear have a certain frequency. People with normal hearing can typically hear from about 50 Hz to about 20,000 Hz (more typically 20 KHz). A 50 Hz sound would be like a low rumbling sound, and a 20 KHz sound would be very high frequency like the whooshing sounds of a cymbal. Most speech ranges from about a few hundred Hz to about 8 KHz, so you can lose a lot of high frequency hearing without serious impact to your ability to understand speech.
At the early stage of hearing loss, high-pitched sounds, such as children’s and female voices, and the sounds “S” and “F” become harder to decipher. Other symptoms of hearing loss include:
- Trouble understanding phone conversations
- Trouble hearing above background noise
- Trouble following a conversation when more than one person speaks at once
- Perception that people are not speaking clearly or mumbling
- Often misunderstanding what people say and responding inappropriately
- Often having to ask people to repeat themselves
- Frequent complaints by others that the TV is too loud
- Ringing, roaring, or hissing sounds in the ears, known as tinnitus
The decibel is a unit to measure the level 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 things:
- 150 dB = fireworks at 3 feet
- 140 dB = firearms, jet engine
- 130 dB = jackhammer
- 120 dB = jet plane takeoff, siren
- 110 dB = maximum output of some MP3 players, model airplane, chain saw
- 106 dB = gas lawn mower, snow blower
- 100 dB = hand drill, pneumatic drill
- 90 dB = subway, passing motorcycle
- 80–90 dB = blow-dryer, kitchen blender, food processor
- 70 dB = busy traffic, vacuum cleaner, alarm clock
- 60 dB = typical conversation, dishwasher, clothes dryer
- 50 dB = moderate rainfall
- 40 dB = quiet room
- 30 dB = whisper, quiet library
Hearing loss can also be caused by your workplace. According to the CDC (Center for Disease Control):
Facts and Statistics
- Four million workers go to work each day in damaging noise. Ten million people in the U.S. have a noise-related hearing loss. Twenty-two million workers are exposed to potentially damaging noise each year.
- In 2008, approximately 2 million U.S. workers were exposed to noise levels at work that put them at risk of hearing loss.
- In 2007, approximately 23,000 cases were reported of occupational hearing loss that was great enough to cause hearing impairment.
- Reported cases of hearing loss accounted for 14% of occupational illness in 2007.
- In 2007, approximately 82% of the cases involving occupational hearing loss were reported among workers in the manufacturing sector.
According to OSHA (Occupational Safety and Health Administration), there are 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.
How can you prevent hearing loss? The most obvious way is to avoid loud noise whenever possible. When exposed, move away from it as soon as you can to minimize the exposure. If that is not a practical solution for you and yours, try using hearing protection, such as earmuffs or earplugs, can be purchased at drugstores, hardware stores, or sports stores. When listening to your personal listening device like your MP3 or IPod, turn it down a few notches. You will get used to it in time. You can also look at the noise rating on many products.
Not sure if you have hearing loss? Consult your doctor to find out. In any case, it is never too late to prevent further loss to you and any loss to the next generations. Shhhhhhhhhhhhhh