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Read the text “Cause of Hearing Loss”. Use dictionary if necessary.

Exposure to loud noise is the second most common cause of hearing loss. Approximately 30 million Americans are exposed to high intensity noise in their workplace, in one in 4 of these workers (or 7.5 million Americans) a permanent hearing loss will develop. Much can be done to prevent noise-induced hearing loss but little can be done to reverse it. Sometimes a single exposure to loud noise is all that is needed, a single hunting trip without ear plugs. Loud noise damages the hair cells in the inner ear and can cause hearing loss, ear ringing and distortion of sounds. The symptoms of noise induced hearing loss are subtle in the early stages. Hearing loss tends to occur first for high-pitched sounds only. Consequently, the volume of sound heard may be unchanged but the quality of it lessens. Speech may be heard but not completely understood. The presence of background noise can make speech hard to understand. Noise induced hearing loss has been reported to be accompanied by a ringing in the ears (tinnitus) in 23% of subjects. Tinnitus can often be more annoying than the hearing loss itself. Treatment of tinnitus is often unsatisfactory. There has been an association between acoustic trauma (noise induced hearing loss) and Meniere's disease which has been reported in a few research articles and text books. However, more recent literature has shown that acoustic trauma is not a causative factor.

Physical measurements of the sound can determine whether it exceeds dangerous levels, and most factories have access to the necessary equipment. Radio Shack also sells a sound level meter for under $40 which will measure noise levels using the "A" Scale. (This is what the designation dBA refers to -- decibels measured in the A Scale.) However, without noise-measuring equipment, the following basic rules can be followed:

1. If it is necessary to shout to hear yourself over a noise, the level of the sound can be damaging.

2. Should ringing in the ears occur after exposure to a loud sound, damage has been done and that sound should be avoided or ear protection used in the future.

3. If diminished hearing or a sense of fullness in the ears is experienced after noise exposure, the level of that noise is damaging.

There are several federal guidelines for noise exposure.

The NIOSH recommended exposure limit (REL) for occupational noise exposure (85 decibels an 8-hour time-weighted average) was reevaluated using contemporary risk assessment techniques 4000-hertz (Hz) audiometric frequency in the definition of hearing impairment. The new risk assessment reaffirms support for the 85-dBA. With a 40-year lifetime exposure at the 85-dBA REL, the excess risk of developing occupational NIHL is 8%considerably lower than the 25% excess risk at the 90-dBA permissible exposure limit currently enforced by the Occupational Safety and Health Administration (OSHA) and the Mine Safety and Health Administration.

Decibel Levels of Environmental Sounds

Source--Dangerous Level dBA SPL
Produces Pain 120-140
Jet Aircraft During Takeoff (at 20 meters)
Snowmobile Tractor Without Cab
Rock Concert
Die Forging Hammer Gas Weed-Whacker Chain Saw Pneumatic Drill 100-105
Home Lawn Mowers 95 to 100 dB
Semi-trailers (at 20 meters)

 

Source-- dBA SPL
Discomfort Level Above 80
Heavy Traffic
Automobile (at 20 meters)
Vacuum Cleaner
Conversational Speech (at 1 meter)
Quiet Business Office
Residential Area at Night
Whisper, Rustle of Leaves
Rustle of Leaves
Threshold of Audibility

 

 

There are also many agents found in industry which can also damage hearing in addition to industrial noise exposure. The most common is tobacco.

Industrial Solvents: The combination of solvents and noise exposure exceeds the damage produced by either also. The effect of solvents is potentiated even more by exposure to ethanol. Organic Solvents found in Industry which are ototoxic include.

- Toluene:Found in paints, thinners, rubbers and in the printing industry.

-Stryene: Found in plastics, rubbers, resins, insulating materials.

- Carbon Disulfide: Found in the textile industry and insecticides.

- Tricholoroethylene:

- Xylene: Found in paint and lacquer industry

- Metals: Lead may also cause hearing loss

- Asphyxiants: Carbon Monoxide

Since there is little that can be done to treat noise induced hearing loss, prevention by avoidance of loud noises is the best course. Compressible foam ear plugs (not water plugs) and ear muffs when fitted properly can decrease the noise exposure level by over 20 dB. EAR Classic plugs have a properly fitted noise reduction rating of 29 dB. When given to subjects to fit themselves the average attenuation was found to be 17 dB.Ear plugs and ear muffs are about equally effective. Muffs cost more but can be used in patients with ear canal disease. Muffs are also hot in warm weather.

For hunting, electronic plugs and muffs can be obtained which make surrounding noise louder so game can be heard, but when firing a gun they muffle the loud noise. Many people will not wear ear plugs in a noisy environment because they think it will make it more difficult to hear others talking. Actually the reverse is true. Ear plugs reduce noise most efficiently in the low frequencies, below the speech range. This will increase the signal to noise ratio of the speech and makes it more easily heard.

New research indicates that several types of drugs when taken before or immediately after noise exposure may mitigate the damage to the inner ear. These drugs fall into three categories:

Anti-oxidants: These drugs may be protective based on the theory that one of the mechanisms in noise inducted hearing loss is the generation of free oxygen radicals. Vitamin E given at 10mg/kg/day to 40mg/kg/day in the guinea pig was protective.;Acetyl-L carnitine a mitrochondrial stabilizer for damage induced by free oxygen radicals, and N-L-acetylcysteine an antioxidant, has been shown to mitigate noise induced hearing loss in the chinchilla. Glutathione is an antioxadant which has been shown to reduce the damage of noise exposure. Researchers have also found that noise induced hearing loss is characterized by a glutathione deficiency state and increase glutathione levels may be protective. Glutathione monoethylester and in combination with R-N6-phenylisopropyladenosine has also been studied in the chinchilla and has been found to be protective.

Glutamate Receptor Antagonist: These drugs may be protective based on the theory that one of the mechanisms in noise induced hearing loss is the generation of Glutamate which binds to post-synaptic glutamate receptors which leads to degeneration of the neurons. Investigated drugs include: caroverine; carbamathione.

Neurotrophins: There is also evidence that neurotrophins (neurotrophin-3) may also be protective.

Remember the most common outcome to noise exposure is a permanent hearing loss.When this occurs the only effective treatment is the use of hearing aids. This is why prevention by avoiding loud noises and wearing ear protectors is so important.

 

III. 1. Answer the questions:

1) What noises are dangerous?

2) What is the main way to prevent hearing loss?

3) What treatment for hearing loss is the most common?

4) What industries are the most dangerous from the point of view of hearing loss?

5) How medicines affect hearing? Which of them are harmful?

 

2. Say whether the following statements are true or false:

1) Hearing loss is a very frequent disease in the United States.

2) Exposure to loud noise is the most common cause of hearing loss.

3) Noise induced hearing loss has been reported to be accompanied by a ringing in the ears.

4) Physical measurements of the sound can determine whether it exceeds dangerous levels, and most factories have access to the necessary equipment.

5) If diminished hearing or a sense of fullness in the ears is experienced after noise exposure, the level of that noise is not damaging.

6) There are also many agents found in industry which can also damage hearing in addition to industrial noise exposure.

7) The most common cause for hearing loss is tobacco.

8) The effect of solvents is potentiated even more by exposure to ethanol.

9) Compressible foam ear plugs (not water plugs) and ear muffs when fitted properly can decrease the noise exposure level by over 20 dB.

10) Ear plugs reduce noise most efficiently in the low frequencies, below the speech range.

11) New research indicates that several types of drugs when taken before or immediately after noise exposure may mitigate the damage to the inner ear.

 

Which word in the list is odd?

1) loud noise, high intensity noise, background noise, permanent hearing loss;

2) noise-induced hearing loss, permanent hearing loss, hearing loss, hearing impairment, loud noise;

3) hair cells, inner ear, chinchilla, ear ringing;

4) distortion of sounds, high-pitched sounds, acoustic trauma, ear ringing;

5) noise-measuring equipment, ear protection, acoustic trauma;

6) industrial solvents, organic solvents, causative factor;

7) organic solvents, toluene, styrene, carbon disulfide, trichloroethylene, xylene, metals, asphyxiates, carbon monoxide;

8) foam ear plugs, water plugs, ear protection, ear muffs, acoustic trauma;

9) ear canal disease, hearing impairment, noise-measuring equipment;

10) inner ear damage, neurotrophins, glutamate receptor antagonist, anti-oxidants.

 

4. Continue the sentences:

1) Exposure to loud noise ….

2) Noise induced hearing loss ….

3) Physical measurements of …

4) If diminished hearing …

5) There are also…

6) The most common …

7) The effect of solvents …

8) Compressible foam ear plugs …

9) Ear plugs …

10) New research indicates that …

 

5. Fill in the blanks with the words from the text:

Exposure to loud … the second most common …of hearing loss. Approximately 30 million Americans are …to high intensity … in their workplace, in one in 4 of these workers (or 7.5 million Americans) a permanent … loss will develop. Much can be done to prevent noise-induced hearing … but little can be done to … it. Sometimes a single … to loud … is all that is needed, a single hunting trip without ear…. Loud … damages the hair cells in the inner … and can cause … loss, … ringing and distortion of sounds.The symptoms of … induced hearing …are subtle in the early stages. Hearing … tends to occur first for high-pitched sounds only. Consequently, the volume of sound heard may be unchanged but the quality of it lessens. Speech may be heard but not completely understood. The presence of background … can make speech hard to understand. Noise induced … has been reported to be accompanied by a ringing in the ears (tinnitus) in 23% of subjects. Tinnitus can often be more annoying than the … itself. Treatment of tinnitus is often unsatisfactory. There has been an association between acoustic trauma (noise induced… ) and Meniere's disease which has been reported in a few research articles and text books. However, more recent literature has shown that .. … is not a causative factor.

 

6. Give synonyms from the text to the following words:

- a small piece of equipment that someone wears in the ear to help to hear;

- disability to hear sounds;

- two parts of the body to the sides of the head that help to hear;

- the trauma related to high level sounds or music;

- a tube of fur or thick cloth which you put into the ears to protect them from sound damage.

 

Последнее изменение этой страницы: 2016-08-29

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