Noise Pollution - Air Pollution - Lecture Slides, Slides of Ecology and Environment

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NOISE

MEASUREMENT

& ABATEMENT

The nature of sound

Sound, a manifestation of vibration, travels in wave patterns throughsolids, liquids and gases.The waves, caused by vibration of the molecules, follow sine functions,typified by the amplitude and wavelength (or frequency)Sound waves of equalamplitude with increasingfrequency from top tobottom

Amplitude and wavelength (period)

Bels and decibels

Sound pressure level

Sound pressure for known sounds

Exposure to high sound levels

Reflecting on noise

Noise" derived from "nausea," meaning seasickness 

Noise is among the most pervasive pollutants today 

Noise is unavoidable for many machines 

We experience noise in a number of ways 

environmental 

cause and victim 

generated by others “second-hand”



Noise negatively affects human health and well-being 

The air into which second-hand noise is emitted and on which it travels is a "commons“, a public good

Local noise regulation



Dr. Paul Herman wrote the first comprehensive noise codes in 1975 for Portland, Oregon with fundingfrom the EPA (Environmental Protection Agency) and HUD (Housing and Urban Development). ThePortland Noise Code became the basis for most other ordinances for major U.S. and Canadianmetropolitan regions.

[18]



Most city ordinances prohibit sound above a threshold intensity from trespassing over property line atnight, typically between 10 p.m. and 6 a.m., and during the day restricts it to a higher sound level;however, enforcement is uneven. Many municipalities do not follow up on complaints. Even where amunicipality has an enforcement office, it may only be willing to issue warnings, since taking offenders tocourt is expensive. 

The notable exception to this rule is the City of Portland Oregon which has instituted an aggressiveprotection for its citizens with fines reaching as high at $5000 per infraction, with the ability to cite aresponsible noise violator multiple times in a single day. 

Many conflicts over noise pollution are handled by negotiation between the emitter and the receiver.Escalation procedures vary by country, and may include action in conjunction with local authorities, inparticular the police. Noise pollution often persists because only five to ten percent of people affected bynoise will lodge a formal complaint. Many people are not aware of their legal right to quiet and do notknow how to register a complaint

Aircraft noise

FA-18 Hornetbreaking soundbarrier

Chart method – adding decibels

Chart method – subtracting background noise

Sound and human hearingPeople generally hear soundsbetween the “threshold of hearing”and the “threshold of pain”In terms of pressure,this is 20

μ

Pa – 100 Pa

The decibel scale was developed from this factand makes numbers more manageableThe decibel scale generally ranges fromapproximately 0 to 130

How Sound is Heard