Noise Pollution

Common Questions Often Associated with Noise Pollution:

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What is Noise Pollution?

A level of noise that contributes to a decreased quality of living and/or eventual hearing loss for the people living in that particular area.

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How does Hearing work and how does Noise Pollution affect it?

Sound waves enter the auditory canal, causing the eardrum to vibrate. The three small bones of the middle ear transmit these vibrations to the inner ear, through which they move as fluid-pressure waves. The Organ of Corti, running the length of the Cochlea, converts these vibrations to nerve impulses which are then carried to the brain by the auditory nerve.

Noise first affects the outer hair cells at the base of the cochlea in the Organ of Corti. These hair cells are associated with high frequency sounds, which are the first sounds lost through Noise Pollution. Fluid vibrations in the inner ear are converted into impulses by the hair cells, which are then carried to the brain by the auditory nerve, resulting in sound. Over a period of time, prolonged exposure to excessive noise levels may result in the complete collapse of individual hair cells, thus affecting the transmission of nerve impulses. Thirty to forty percent of the 16,000 sensory receptor hair cells in the Organ of Corti can be destroyed before any noticeable amount loss occurs.

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What are common responses to different Noise Levels?

Sound is measured in units called decibels. Normal hearing begins at levels of zero decibels with increasing intensity to 140 decibels. Levels as low as 60 decibels can be considered intrusive and levels of 80 decibels are considered annoying. 90 decibels may even cause hearing damage. Noise is noticeable at this level, however, people do not tend to move away from noise until levels increase to 100-110 decibels or more. Levels greater than this will force one to cover their ears due to painfully loud sounds.

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What are some examples of Noise Levels?

Decibels

0
40
60
70
80
90
100
110
120

Source

barely detectable sounds whispers, dripping faucet quiet conversation, hum from refrigerator garbage disposal, passing car aircraft cabin lawn mower, vacuum motorcycle, power saw, rock concert model airplane, automobile kicker box firearms

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What are the signs of Hearing Damage?

To understand signs of hearing loss, first the possible hearing loss types must be explored.

There are three forms of hearing loss:

Type 1- Temporary threshold shift

This happens in response to short exposures to loud noises like rock concerts. Signs include unclear hearing, ringing ears sensation, and the feeling that the ear is "full." Symptoms may last for several hours, but they are reversible. In fact, temporary threshold shift is the only reversible type of hearing damage.

Type 2- Acoustic trauma

Acoustic trauma happens when an explosion of noise greater than 130 decibels occurs from sources like firearms or explosions. Signs include mechanical destruction of the ear. The tympanum is shattered and the hair cells are severely damaged. The effects are permanent and instantaneous.
 

Type 3- Noise induced hearing loss

Occurs through long term exposure to loud noises like drums or construction equipment. First signs is the loss of the ability to hear high frequency (about 6,000 Hz) sounds. This is the primary symptom of presbycusis, or hearing loss over time due to exposure to noise. Symptoms of this type are painless and gradual. The disability is not even noticed until significant damage has occurred. Fifty percent of hair cells can be destroyed without the individual noticing. The result are people who share a false sense of security until the damage becomes noticeable. by this time, it is too late and the hearing is permanently damaged.
 

Warning Signs of Hearing Impairment Include:

  • Difficulty in hearing after being exposed to loud noise
  • A "buzzing" sensation after leaving a loud environment
  • When temporary threshold shifts occur
  • Pain in the eardrum after high noise exposure
  • When noise exposure causes nausea, dizziness, or vertigo
  • When prolonged noise exposure makes one irritable

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What does the Government say about Noise Pollution?

The Occupational Safety and Health Administration (OSHA) has established standards regulating the amount of time individuals may be exposed to noises at decibels that cause hearing damage. These standards range from 8 hours per day at 90dB of 1/4 hour or less to levels of 115 dB

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In 1972, the government set the first law for noise control, the Noise Control Act. It created regulations for commercial products like trucks, buses, and jackhammers that emitted high decibel noise levels. The law also required the EPA, Environmental Protection Agency, to create a labeling system for these products and conduct studies on the health impacts of noise. In 1978, the Quiet Communities Act was added to the law, authorizing the EPA, state and local governments to work together to create noise programs. The Act also provided federal funding for these programs.

During the Reagan administration in 1982, this funding was eliminated and the EPA's office of Noise Abatement and Control was disbanded. Only fifteen of 1100 anti-noise programs are still functioning. The laws regulating noise are no longer enforced, and standards were set only for air compressors, motorcycles, trucks, and waste compactors.

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Is Hearing Damage reversible?

Temporary hearing loss due to sudden exposure to loud noises is usually reversible and lasts only a few hours. Long term exposure (considered 16-48 hours) can cause impairment lasting up to two days depending on the intensity and length of exposure.

Prolonged and regular exposure, even to everyday noise levels, can cause permanent damage. The sound of an electric shaver or food processor can average 85 decibels which may cause slight permanent hearing loss over an eight hour period. Sensitive individuals may experience hearing loss at 70 decibels. Every time the noise level increases by 5 decibels, the time required to cause damage is halved. Rock concerts can reach 120 decibels and may cause damage in 30 minutes. Exposure to high decibel noises damages hair and noise receptor cells in the ear and affects the auditory nerves and choclear structures. This type of damage is irreversible.

Sufferers of partial hearing loss may also experience tinnitus, a ringing or buzzing sound in the head. It is reversible in mild cases. In some cases, the sound can reach 70 decibels and is usually reversible. Partial hearing loss may be helped by the use of hearing aids in some cases.

For more information on hearing aids:

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Other Pages

Here are some other useful sites:

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Some information on this page and related pages obtained from those sites listed above. Page written by Kenneth B. Fischer, Jen Lamb, Jen Koch, and Brian Weersing.