The noise problems of the past are incomparable with those plaguing modern society: the roar of aircraft, the thunder of heavily laden lorries and the thumps and whines of industry provide a noisy background to our lives. But such noise can be not only annoying but also damaging to the health, and is increasing with economic development.
Aging, some drugs, head injuries and too much noise can all cause lasting damage to hearing. This handout discusses the most common type of permanent hearing loss--the loss that results from too much noise.
Long exposure to noise can damage the soft tissue of the inner ear. Cells and nerves in the inner ear are destroyed by continuous or repeated exposure to loud sounds. If enough cells and nerves are destroyed, hearing is permanently damaged.Minor decreases in hearing are normal after age 20. Hearing problems usually come on gradually, and rarely end in complete deafness.There are many causes of hearing loss. They can be divided into 2 main categories:
* Conductive hearing loss (CHL) occurs because of some mechanical problem in the external or middle ear. The three tiny bones of the ear (ossicles) may fail to conduct sound to the cochlea or the eardrum may fail to vibrate in response to sound. Fluid in the middle ear can cause CHL.
* Sensorineural hearing loss (SNHL) results from a dysfunction of the inner ear. It most often occurs when the tiny hair cells (called cilia) that transmit sound through the ear are injured. This type of hearing loss is sometimes called "nerve damage," although this is not accurate.
More than half citizens of Europe live in noisy surroundings; a third experience levels of noise at night that disturb sleep. n the USA in 1990 about 30 million people were daily exposed to a daily occupational noise level above 85 dB, compared with more than nine million people in 1981; these people mostly in the production and manufacturing industries.Prolonged or excessive exposure to noise, whether in the community or at work, can cause permanent medical conditions, such as hypertension and ischaemic heart disease.
Noise-induced hearing loss (NIHL) is a preventable hearing disorder that affects people of all ages and demographics. According to a position statement released by the American Academy of Audiology in 2003, "The average, otherwise healthy, person will have essentially normal hearing at least up to age 60 if his or her ears are not exposed to high noise levels" (American Academy of Audiology [AAA], 2003). Unfortunately, around 30 million adults in the United States are exposed to hazardous sound levels in the workplace
The effects of listening to music turned up too loudly can be permanent.As you pass some of these young people, you can actually hear the music radiating from under those little headphones,” says Kileny, also a professor in the Department of Pediatrics and Communicable Diseases and a member of the Geriatrics Center. “That is a sure sign that the individual listening to that music is listening at a level that is too loud, and, therefore, in the long run is risky to the status of their hearing.”
With these personal audio players, there are no built-in electronic safety cut-offs or safety devices that preclude listening at a dangerous level or that at least inform the wearer that he or she has reached a level which might be risky to hearing.A new study shows an association between cardiovascular disease and age-related hearing loss - particularly in women who've had a heart attack,
Noise can adversely affect performance, for example in reading, attentiveness, problem solving and memory. Deficits in performance can lead to accidents.Noise can cause hearing impairment, interfere with communication, disturb sleep, cause cardiovascular and psycho-physiological effects, reduce performance, and provoke annoyance responses and changes in social behaviour. The main social consequence of hearing impairment is the inability to understand speech in normal conditions, which is considered a severe social handicap.
Hearing experts are concerned that hearing loss will take place because exposure to music through these devices can be both loud and long. With the new MP3 players, such as the iPod, significant improvements in sound quality are possible in smaller and more portable devices. Sound quality, portability and convenience translate into more time spent listening to music, which makes the potential for damage even greater.
Several studies have focused on schools around airports for assessing how this specific source affects children’s performance and health. Acoustical insulation has been installed in some schools, but the potential negative and positive effects of interventions have not been researched thoroughly enough to provide policy-makers with clear guidance.
You might want to accompany that next rock concert with a few antioxidant cocktails, if new animal research is correct.
In experiments with guinea pigs, researchers found that a combination of antioxidants -- vitamins A, C and E, plus magnesium -- seemed to protect the animals from noise-induced hearing loss.
A clinical trial will soon be underway to test the effects of the nutrients on soldiers who are exposed to loud noises during training, Dr. Colleen G. Le Prell, the lead author of the current study, told Reuters Health.
But until more is known about the antioxidants' effects on human hearing, it's probably not a good idea to crank the volume on your iPod. If these antioxidants are effective, it's not clear what doses people would need to protect their hearing, according to Le Prell, a researcher at the University of Michigan Hearing Research Institute in Ann Arbor.
"We don't yet have human data that confirm effectiveness of these agents at any given dose," she said.
The findings, published in the latest issue of Free Radical Biology & Medicine, are based on experiments with guinea pigs exposed to the decibel equivalent of a jet engine at take-off.
One hour before the noise exposure and once-daily for 5 days after, the animals were given either the vitamin-magnesium combination, just one of the nutrients or a placebo supplement. In the end, the researchers found, animals given the antioxidant combo showed significantly less hearing loss than the other groups did.
According to Le Prell's team, the pre-exposure treatment may have helped by suppressing the development of cell-damaging substances called free radicals. The post-noise doses, in turn, may have lessened harm to the auditory nerves.
Along with soldiers, others regularly exposed to noise pollution could potentially benefit from the antioxidant combo -- such as pilots, construction workers or musicians, and even fans of NASCAR, rock concerts or MP3 players -- according to Le Prell.
For now, she suggests that people try to get the recommended amounts of magnesium and vitamins A, C and E through diet.
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