Transcript INDUSTRIAL NOISE - Indiana University of Pennsylvania

INDUSTRIAL NOISE
…the nature & effects of exposure to
excessive noise…..I SAID, THE
NATURE & EFFECTS OF
EXPOSURE TO
EXCESSIVE NOISE
What is sound?
“… any pressure variation that the human
ear can detect”
 “…..sensation produced through the organs
of hearing usually by vibrations transmitted
in a material medium, commonly air.”
 If a tree falls in a forest…
 Noise = unwanted sound!
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What is the need?
Estimates show that 16.9% of the working
population are employed in jobs where
noise levels exceed 85 dB.
 It is estimated that 1.7 million workers in
the US between 50 and 59 years of age have
compensable noise-induced hearing loss.
The potential cost to industry could exceed
$500 million.
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Properties of Sound
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WAVELENGTH
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FREQUENCY
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PITCH
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INTENSITY
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PRESSURE
HOW DO WE HEAR?
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OUTER EAR
(funnels waves to
eardrum)
MIDDLE EAR
(transfers sound energy
from outer to inner ear)
INNER EAR
(has receptors for
hearing and position
sense)
THE COCHLEA
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Sensory organ for
hearing
Organ of Corti
Frequency is a
function of position;
i.e.., hairs at base
respond to high
frequencies
EAR’S NATURAL DEFENSES
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Secretion of wax
Hairs in outer ear
Bent ear canal
Contractile muscle in
eardrum/middle ear
Air-filled middle ear
NON-NOISE-INDUCED
HEARING LOSS
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Physical blockage of
auditory canal
Traumatic damage
Disease damage
Hereditary or prenatal
damage
Drug-induced damage
Presbycusis
NOISE-INDUCED DAMAGE
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Physiological
– Temporary & permanent
threshold shifts
– Acoustic trauma vs. noiseinduced hearing loss
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Psychological
Cardiovascular
Speech interference
Other
The effect that excessive noise
has on an individual’s hearing...
Noise intensity (sound pressure level)
 Frequencies/pitch
 Time/type relationship
(continuous/intermittent)
 Duration of exposure episodes
 Total work duration
 Individual susceptibilities
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Common sounds in decibels
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Sound is measured in decibels (dB)
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10 dB – human breathing, rustle of leaves
20 dB – average whisper
30 dB – average residence w/o stereo playing
50 dB – average office
60 dB – near freeway auto traffic
80 dB – school cafeteria
90 dB – noise factory, noisy urban street
100 dB – loud horns at 10 feet away
110 dB – accelerating motorcycle at a few feet away
120 dB – hard rock band
130 dB – threshold of pain
140 dB – near jet engine
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Common industries…
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Construction
Mining
Agriculture/forestry
Manufacturing
– Textile, food, lumber, furniture, paper, printing, chemicals,
petroleum, leather, metal, machinery, electronics etc.
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Services
– Auto repair, other repair services, etc.
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Transportation
– Passenger transit, trucking and warehousing, transportation
by air, electric, gas, and sanitary services
Steps in identification
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Preliminary noise survey
– Carried out at work areas where it is difficult to
communicate in normal tones
– When workers notice that sounds are muffled or they
develop ringing in their ears
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Detailed noise survey
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How noisy is each work area?
What equipment or process is generating noise?
Which employees are exposed to the noise?
How long are they exposed?
TLVs and PELs
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TLV’s for Noise
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8 hrs
4 hrs
2 hrs
1 hr
.5 hr
.25 hr
85 dB
88 dB
91 dB
94 dB
97 dB
100 dB
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PELs for Noise
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8 hrs
4 hrs
2 hrs
1 hr
.5 hr
.25 hr
90 dB
95 dB
100 dB
105 dB
110 dB
115 dB
Impact Noise
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Exposure to impulsive or impact noise
should not exceed 140 dB peak sound
pressure level
Permissible Exposure Levels
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90 dB is established
PEL
However, at 85 dB one
must implement an
effective hearing
conservation program
OSHA Hearing Conservation
Program (29 CFR 1910.95)
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Noise monitoring
Audiometric testing
program
Employee follow-up
and referral
Hearing protection
Employee training
Recordkeeping