Stephen F. Austin State University
February 2002
In our everyday lives we hear many different sounds. Many times we hear noises that are harmful to our hearing. When we hear noises that are too loud for a long amount of time, something called Noise-Induced Hearing Loss can occur. In Noise-Induced Hearing Loss the inner structures of the ear, which are very sensitive, are damaged.
In the normal system, sound waves are transformed into electrical energy. The sound waves are first caught by the outer ear. From the outer ear they travel to the middle ear, which leads to vibrations in the ear drum. These vibrations are carried through three small bones in the middle ear called ossicles. Here the vibrations are magnified and then carried to the inner ear. After entering the inner ear they flow through fluid in the cochlea, the part of the ear that allows you to hear. The cochlea contains many hair cells which are moved by the fluid and then signals are carried to the brain and are perceived as sound. Different levels and variations of sounds have different impacts on the motion of the hair cells. Very loud noises for long amounts of time can cause damage to the hair cells, which can cause Noise-Induced Hearing Loss (NIDCD, 2002).
Noise-Induced Hearing Loss can be temporary or permanent. The symptoms increase gradually as a person is exposed more and more to continuous loud noises. Sounds begin to be less clear and muffled. Sometimes a person may not even realize they have a hearing loss (NIDCD, 2002). Noise-Induced Hearing Loss can also be accompanied by pitch distortion, speech impairment and tinnitus, which causes ringing in the ears (Prasher, 1998).
Noise-Induced Hearing Loss should be studied for many different reasons. It is very important for everyone to know the risks of hearing really loud noise for an extended amount of time. By doing research, we can acknowledge these risks and inform the public of ways to prevent hearing loss. Also, research can allow us to come up with many different ways to treat Noise-Induced Hearing Loss. It is very important for everyone who experiences these loud noises to be able to know how to prevent hearing loss, or how to get help if loss has already occurred. If there was more information and research available on Noise-Induced Hearing Loss, a huge population of people could prevent hearing loss, even though there are many who already experience it.
Many people all over the world experience loud noises on the job, during leisure time, or at home, and do not even realize they are at risk for a hearing loss. Carpenters, construction workers, loggers, firemen, policemen, factory workers and many more jobs involve continuous loud noises. Rock stars who play many shows throughout their lives experience hearing loss. Symphony musicians and percussionists are also at risk. People of all different ages are at risk for hearing loss. Even younger people who attend concerts, go to clubs or just listen to loud music are at a risk for hearing loss. At home, vacuum cleaners, lawn mowers, power tools, and many more items are used, which can also cause a loss. As you can see, there are many different types of people who experience continuous loud noises and many items that can cause hearing loss.
Approximately one-third of Americans have been affected by loud noises (NICDCD, 2002). Many different loud noises can cause hearing loss. Usually, hearing sounds of more than 75 decibels (dB) are likely to cause temporary hearing loss (NIDCD, 2002). To give some examples, a jet taking off emits loudness of about 140 dB. Attending a rock concert or using a chainsaw can give off 110 to120 dB, and stereo headphones can have a loudness of 100 dB. Conversation is not nearly as loud compared to the previous sounds, giving off a loudness of only 60 dB. A whisper gives off only a mere 30 to 40 dB (Rabinowitz, 2000). Now that you have an idea of exactly how loud certain sounds are, we can begin talking about when a hearing loss can originate, for example, during childhood.
The childhood years have a great impact on whether or not Noise-Induced Hearing Loss can occur. If a parent does not realize early in a childís life that hearing loss can be brought about by continuous loud noises, then there is a greater chance of damage once a person gets older. Some types of toys made for children can generate enough sound to cause a hearing loss that could be permanent (Rabinowitz, 2000). Children around the world enjoy blasting their favorite music on the stereo. There is a chance that children who listen to loud music often may need hearing aids later on in life (Current Health 2, 2001). In a recent study, it was found that people who use portable stereos regularly and have a history of childhood ear infections can obtain a higher degree of hearing loss than from attending rock concerts two times a month or more or working in an environment with a lot of noise (Napoli, 1999). A study performed in Germany showed that one out of every ten 18-year-olds may already be suffering from a hearing loss. Because of this, Germany is trying to pass a law to limit the maximum stereo volume to 90 dB (Charles, 1997). Some say that the problem of hearing loss in children is likely to get worse in years to come. If protection does not occur at an early age, todayís children could have more hearing problems as they get older (Childs, 2001).
Hearing loss may also occur when a person is older. There are many jobs that involve continuous loud noises, and certain jobs involve more noise than others. People who work in the manufacturing industry are very exposed. Some of these people are exposed to an average of 85 dB or more (Nash, 2000). Often there is a lack of concern for these workers because only a small amount of hearing impairment is apparent. There is a poor system of recording hearing on the job and hearing loss has often been underreported. Many companies that need hearing programs do not have them (Nash, 2000). There are many companies, however, that do follow strict regulations. The Occupational Safety and Health Administration makes regular inspections and gathers information about employees, machines, the working environment, employers and hearing loss on the job (OSHA, 2002, sect. 3, ch. 5). Hearing Conservation Programs are also used to eliminate as much hearing loss on the job as possible. Hearing Conversation Programs for industrial workers must examine the workplace to look for possible hazards, establish a training program for employees, and monitor the program to see its effectiveness. It is very important noise issues be addressed and that hearing programs and protectors be used in the right way or there is more of a chance of hearing loss (Nash, 2000).
The manufacturing industry is not the only industry where Noise-Induced Hearing Loss has a chance of occurring. Construction workers also experience a lot of loud noise on the job. There is not much information available on construction workersí exposure to loud noise, how much they use hearing protection, or how many employers provide Hearing Conservation Programs. There is a standard that requires hearing protection and programs to be available to employees exposed at or above 85 dB for an eight hour time period. In a recent study at a construction site, it was recorded that workers experienced noises above this level during a whole project (Lusk, 1998). However, it is hard to study construction workers because they are frequently changing job sites, which makes noise exposure irregular. The construction industry has more lenient regulations than other fields and does not have an organization to collect data on noise hazards. Lusk (1998) performed a study in order to determine whether operating engineers or carpenters experienced a greater loss. It was found that operating engineers had the most exposure to noise, use of protective devices and perceived hearing loss, while carpenters were the opposite. It is important to realize when studying Noise-Induced Hearing Loss on the job that different trades have different amounts of exposure to loud noise and implement the use of hearing protection differently.
There are many different ways to prevent and treat hearing loss in a clinical sense. Wearing ear plugs or using other protective devices is one very common way to prevent Noise-Induced Hearing Loss. When ear plugs or other hearing protection devices are worn correctly they can have a positive effect. If they do not fit correctly or are not worn during the whole exposure, they may not work well. There are a variety of hearing protective devices and ear plugs available on the market so that it is possible to find the one that fits (Nash, 2000). With medical advancements, new treatments are being studied and may end up replacing ear plugs and other protective devices. An oral steroid drug has been used to test for hearing loss prevention but caused too many side effects and was abandoned (Borlik, 1998). Other treatments have been studied that have been successful. An Army-Navy research team came up with a treatment to prevent hearing loss. The team used tiny tubes and implanted them into the inner ear. On the outside of the ear, the tube is connected to a reservoir and pump that releases a steroid into the inner ear. The drug coats the hair cells to prevent them from damaging. So far three patients have been treated and have regained partial hearing from this procedure (Borlik,1998). There are also other types of drugs that have been tested. A noise control pill to prevent hearing damage may be on the market soon. The pill can control the amount of noise that is stimulated in the ear so that damage can be limited (Abdulla, 1998). It has also been found that certain neurotropins, proteins, or free-radicals may limit noise damage when administered (Abdulla, 1998).
There are many ways to prevent hearing loss without the use of drugs. One way to protect hearing is through sound conditioning, which involves giving a low exposure to an audible stimulus before noise trauma can occur. There is another process called toughening that can be used, which involves periodic pre-exposure to high sound levels (Prasher, 1998). In the workplace, effective training and Hearing Conservation Programs are used to reduce the risks of hearing loss. Noise-Induced Hearing Loss can be treated with hearing aids and also counseling. By using many different hearing protection devices and treatments, we are learning how to prevent and how to help hearing loss.
Noise-Induced Hearing Loss is being studied more now than it has in the past. Many new treatments and therapies are being used to help hearing loss. With medical advances, we are able to study how to help hearing loss more in depth. More research should be done on children because childhood is when a hearing loss can begin. Also, more information should be publicized on how much damage that everyday devices can do. The involvement of prevention in the workplace is very well developed and hopefully will expand to other areas such as households and everyday life.
References:
Abdulla, S. (1998). Pills may replace ear-muffs for protection against damaging noise. The Lancet, 351 (9113), 1411.
Borlik, A. K. (1998). Navy medical breakthrough could repair hearing loss. Retrieved February 10, 2002, from http ://www .defenselink .mil/news/ Sep1998/ n09171998_9809172.html
Charles, D. (1997). What did you say: personal stereos and club sound systems are deafening a generation, German research suggests. New Scientist, 155 (2089), 12.
Childs, D. (2001). Turn down the music. Retrieved February 10, 2002, from http://www.abcnnews.com.
(2001). Listen up! Current Health 2, 28 (4), 2.
Lusk, S. J., Kauffman, M. J., & Sirkka, A. (1998). Use of hearing protection and perceptions of noise exposure and hearing loss among construction workers. American Industrial Hygiene Association Journal, 59 (7), 466-470.
Napoli, M. (1999). Loud music, headphones and hearing loss. Health Facts.
Nash, J. L. (2000). Whatís wrong with hearing conversation. Occupational Hazards, 62, (1). 41-44.
(2002) NIDCD health information. Retrieved February 10, 2002, from http://www.nidcd.nih.gov/health/pubs_hb/noise.htm.
Occupational Safety and Health Administration. (2002). OSHA technical manual. Retrieved February 10, 2002, from http://www.osha.gov/dts/osta/otm/otm_iii_5.html.
Prasher, D. (1998). New strategies for prevention and treatment of noise-induced hearing loss. The Lancet, 1, 1240-1243.
Rabinowitz, P. M. (2000). Noise-induced hearing loss. American Family Physician, 61, (9), 2749-2759.