Home
Noise Effects On Human Health
Articles - Noise Pollution

Noise can be defined as an unwanted sound created by pressure variation in the air / environment and detected by the ear of different lives.

How Do we Hear

Noise pollution, usually called environmental noise in technical venues, is displeasing human or machine created sound that disrupts the environment. The dominant form of noise pollution is from transportation sources, principally motor vehicles. The word "noise" comes from the Latin word nausea meaning "seasickness", or from a derivative (perhaps Latin noxia) of Latin noceō = "I do harm", referring originally to nuisance noise.


  • Main Effects of Noise on Human Health could be listed as -
  • Hearing
  • Cardiovascular Health
  • Annoyance

Sources Of Noise
The overarching source of most noise worldwide is generated by transportation systems, principally motor vehicle noise, but also including aircraft noise and rail noise. Hybrid vehicles for road use are the first widely sold automobiles in 100 years to achieve significant noise reduction. Poor urban planning may also give rise to noise pollution, since juxtaposition of industrial to residential land uses, for example, often results in adverse consequences for the residential acoustic environment.

Besides transportation noise, other prominent sources are-

  1. Office equipment,
  2. Factory machinery,
  3. Appliances,
  4. Power tools,
  5. Lighting hum and
  6. Audio entertainment systems.
  7. BPL (Broadband Over Power Line)

Furthermore, with the popularity of digital audio player devices, individuals in a noisy area might increase the volume in order to drown out ambient sounds. Construction equipment also produces noise pollution.

  • Noise from recreational vehicles has become a serious problem in rural areas.
  • All Terrain Vehicles (ATVs), also known as quads, have increased in popularity and are joining the traditional two wheeled dirt motorcycles for off-road riding.

Hearing Mechanism
The mechanism of hearing. Sound waves enter the outer ear and travel through the external auditory canal until they reach the tympanic membrane, causing the membrane and the attached chain of auditory ossicles to vibrate. The motion of the stapes against the oval window sets up waves in the fluids of the cochlea, causing the basilar membrane to vibrate. This stimulates the sensory cells of the organ of Corti, atop the basilar membrane, to send nerve impulses to the brain.




To learn more about how you hear, visit page "I Love What I Hear - Hearing" hosted by National Institute on Deafness and Other Communication Disorders (NIDCD): Improving the lives of people who have communication disorders


The physiology of hearing
Hearing is the process by which the ear transforms sound vibrations in the external environment into nerve impulses that are conveyed to the brain, where they are interpreted as sounds. Sounds are produced when vibrating objects, such as the plucked string of a guitar, produce pressure pulses. 

Function of the ossicular chain
In order for sound to be transmitted to the inner ear, the vibrations in the air must be changed to vibrations in the cochlear fluids. There is a challenge involved in this task that has to do with difference in impedance—the resistance to the passage of sound—between air and fluid.

Balancing Of Body
Balance, or one’s sense of equilibrium, is controlled through the vestibular system that is also contained in the inner ear. The vestibular organs share the temporal bone space with the cochlea. These organs also share the same fluid that is in the cochlea.
Balance and equilibrium help us stay erect when standing, know where we are in relation to gravity, and help us walk, run, and move without falling. The functioning of the vestibular system depends on information from many systems, hearing as well as vision and muscle feedback.

The vestibular system consists of three semicircular canals , the utricle , and the saccule . Each of the semicircular canals lies anatomically in a different plane, each plane at a right angle to each other. Thus, each deals with different movement: up and down, side to side, and tilting from one side to the other. All contain sensory hair cells that are activated by movement of inner ear fluid (endolymph). As the head moves, hair cells in the semicircular canals send nerve impulses to the brain by way of the vestibular portion of the acoustic nerve (VIII cranial nerve). These nerve impulses are processed in the stem of the brain and in the brain's cerebellum.

The ends of the semicircular canals connect with the utricle, and the utricle connects with the saccule. While the semicircular canals provide information about movement of the head, the sensory hair cells of the utricle and saccule provide information to the brain (again through the vestibular portion of the acoustic nerve) about head position when it is not moving.

The mechanism for chronic exposure to noise leads to –

  • Physical Trauma
  • Hearing Loss

Physical (Accoustic) Trauma / Hearing loss can be clasified  in following  categaries.

  • Accoustic Trauma: In this case the hearing loss is permanent and it occurs due to exposure of sudden & very high noise level for a short duration. Ear drum and other related component are completely destroyed. Noise level in this case remains 160dB and above.
  • Temporary Threshold Shift:  this may be defined as the temporary hearing loss due to momentarily destruction/failure of hearing mechanism, at noise level 140dB↑.
  • Permanenet Threshold Shift:  It occurs after long term exposure of higher noise level then prescribed i.e. above 70dB. In this case hearing is lost permanently
  • Permanent loss

Further, the hearing loss can also be specified in terms of percentage loss i.e. 10%, 20%,…..90%, 95% loss etc. this phenomenon is most prevalent in case of aged persons.


Important Note: The research findings proved that aging is an almost  insignificant cause of hearing loss, which instead is associated with chronic exposure to moderately high levels of environmental noise.


Cardiovascular - Effects

High noise levels can contribute to the following disease –

  • Cardiovascular effects and exposure to moderately high (e.g. above 70 dBA) levels during a single eight hour period causes a statistical rise in blood pressure of five to ten mmHg;
  • A clear and measurable increase in stress;
  • Vasoconstriction leading to the increased blood pressure noted above
  • Increased incidence of coronary artery disease.

Annoyance - Effects
Though it pales in comparison to the health effects noted above, noise pollution constitutes a significant factor of annoyance and distraction in modern artificial environments:

  1. The meaning listeners attribute to the sound influences annoyance, so that, if listeners dislike the noise content, they are annoyed. Its role in human life is subjective. What is music to one is noise to another.
  2. If the sound causes activity interference, noise is more likely to annoy (for example, sleep disturbance)
  3. If listeners feel they can control the noise source, the less likely the noise will be annoying.
  4. If listeners believe that the noise is subject to third-party control, including police, but control has failed, they are more annoyed.
  5. The inherent unpleasantness of the sound causes annoyance.
  6. Contextual sound. If the sound is appropriate for the activity it is in context. If one is at a race track the noise is in context and the psychological effects are absent. If one is at an outdoor picnic the race track noise will produce adverse psychological and physical effects.


A 2005 study by Spanish researchers found that in urban areas households are willing to pay approximately four euros per decibel per year for noise reduction.


Mitigation and Control of Noise Pollution
In consideration of potential impact of vibration and noise on human health, suitable preautionary measures are required to be taken in order to contain or reduce the intensity of noise. Providing barriers is one of the meaningful way to mitigate the noise effect on human health. The barriers could be so designed that either it mitigates or contains the noise. Barriers can be provided in multiple stages depending upon the intensity of generation source, audible area, and consequence of noise to surroundings. Bow & Tie approach may be deployed as done in case of Safety Case Preparation.
Following variety of effective strategies for mitigating adverse sound levels could be utilized-

  • use of noise barriers,
  • limitation of vehicle speeds,
  • alteration of roadway surface texture,
  • limitation of heavy duty vehicles,
  • use of traffic controls that smooth vehicle flow
  • to reduce braking and acceleration,
  • innovative tire design and other methods.

Thousands of case studies indicating substantial improvement in roadway planning and design. The most important factor in applying these strategies is a computer model for roadway noise, that is capable of addressing

o    local topography,
o    meteorology,
o    traffic operations and
o    hypothetical mitigation.

Costs of building in mitigation is often quite modest, provided these solutions are sought in the planning stage of a roadway project.

  • Aircraft noise can be reduced to some extent by design of quieter jet engines. This strategy has brought limited but noticeable reduction of urban sound levels. Reconsideration of operations, such as altering flight paths and time of day runway use, have demonstrated significant benefits for residential populations near airports.
  • Exposure of Industrial noise on workers has the longest history of scientific study, having been addressed since the 1930s. This scientific studies have emphasized
  • Redesign of industrial equipment, shock mounting assemblies and physical barriers in the workplace. Innovations have had considerable success; however, the cost of retrofitting existing systems is often rather high.


Add this page to your favorite Social Bookmarking websites
Reddit! Del.icio.us! Mixx! Free and Open Source Software News Google! Live! Facebook! StumbleUpon! TwitThis Joomla Free PHP
 
 

Polls

Are you aware of hazards posed by Methane
 
Copyright © 2008 EnviroSpectra Welfare Society

Register Cheap Domains | Indian Domain Registrar | Human Edited Directory | SEO Web Directory | Exam Result | Web Hosting Demo | India Real Estate | All About Influenza | Webmaster Blog | Become a Reseller

Webmasters Forum | Become a Reseller | Ministry of Environment & Forests | Central Pollution Control Board