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sound
a vibration that propagates as a mechanical wave of pressure and displacement through some medium
noise
is basically any unwanted sound
it is measured in dB units
characteristics of noise
sound pressure
frequency
duration
time of the day
location
intermittency
kinds of noise
continuous
variable
intermittent
impulse or impact
chemical & instrumental
variable noise
manufacturing & construction noise
different operations or different noise sources cause the sound changes over time
impulse noise
is a category of noise which includes unwanted, almost instantaneous sharp sounds
caused by electromagnetic interference, scratches on the recording disks, & ill synchronization in digital recording & communication
continuous noise
is noise which remains constant & stable over a given time period
intermittent noise
if there is a mix of relatively quiet & noise period
noise pollution
refers to a type of energy pollution in which distracting, irritating, or damaging sounds are freely audible
in this type of pollution, contaminants are not physical attributes, but waves which interfere with the naturally occurring waves of a similar type in the same environment
sources of noise pollution
household sources
social events
commercial & industrial activities
transportation
sources of industrial noise
construction activities
noise created by
agricultural equipment
manufacturing industries
household
is an industry in itself and is a source of many indoor noises
sources of indoor noise
entertainment equipment in the house
Domestic gadgets
hearing problems
reduces our sensitivity to sounds that our ears pick up unconsciously to regulate our body’s rhythm
health issues
Excessive noise pollution in working areas and even in our homes can influence psychological health
cardiovascular noises
High intensity noise causes high blood pressure and increases heart beat rate as it disrupts the normal blood flow
how to control noise pollution
control at source
control in the transmission path
using protective equipment
noise control techniques
sound insulation
sound absorption
vibration damping
public education & awareness
noise
derived from the Latin word “nausea“
Unwanted sound
originates from human activities, especially the urbanization
increasingly omnipresent, yet unnoticed form of pollution
Could come from vehicles
characteristics of sound
frequency
sound level (pitch)
frequency
function of the sound’s wavelength and the transmitting medium and is expressed as:
f = v / λ
has 3 zones
3 zones of frequency
infrasonic
audible
ultrasonic
categories of sound
wide band
narrow band
impulse
wide band
wide range of frequencies
narrow band
narrow range of frequencies
impulse
a temporary sound that may or may not be repetitive
most significant sources of damaging noise
occupational music
loud music
airports
sound pressure level
measured as dB
sound level
dB(A)
filtered soun
measuring devices for sound
sound pressure level meter
sound level meter
audiometer
soung pressure level meter
measures sound as a flat response
dB
sound level meter
measures the filtered sound, dB(A)
Some very low – frequency sound and much of the very high - frequency sound are filtered by the meter and the measured sound represents the hearing of human ear
audiometer
measures the hearing ability at various frequencies producing an audiogram
general effects of noise
hearing loss
heart disease
sleep disruption
mental & social well-being
danger to people
effects of noise on human health
Very loud impulse can burst the ear drum, causing mostly temporary loss of hearing
A torn ear drum heals poorly and can result in permanent damage
The bones in the middle year are not usually damaged by loud sounds but they can be hurt by infections
Middle ear infection can be debilitating, since our sense of balance depends on middle ear
Very loud sounds will stun the hair cells and cause them to cease functioning though most of the time, temporary and can be healed with
time
When the insult to the ear is prolonged, the damage can be permanent and cannot be corrected by hearing aids
Permanent damage to young people is inflicted by most frequently loud music
Loud music does more than cause permanent damage, it is, in the Darwinian sense, synonymous to danger
The human body reacts to loud noise as to protect itself from imminent danger
The bodily reactions include the following:
the eyes dilate
adrenaline flows
blood vessels dilate
heartbeat is altered
senses are altered
blood thicken
Noise cause other ailments such as nervous tension, headaches to neuroses
Noise also disturbs unborn children, and sometimes
cause seizures in epileptics
People who live and work in noisy environments have measurably greater general health problems, are grouchy and ill – tempered and have trouble concentrating
Noise that deprives one of sleep carries with it an additional array of health problems
Most importantly, we cannot adapt to high noise levels
OSHA
Occupational Health and Safety Act
the most effective single legislation to pass congress in the noise control area
Regulations Promulgated by OSHA
Limits of industrial noise
Sound levels greater than 115 dB(A) are clearly detrimental and should not be permitted
Industrial noise is mostly constant over an 8 – hr working day
Community noise is intermittent noise.