1984-07 July IBEW Journal.pdf - International Brotherhood of ...

S~FETYTIPS
for you and your family
NOISE-AN OCCUPATIONAL HEALTH HAZARD
Do you find yourself turnmg up the volume of the TV or
radio when others thmk u 's And
Do you have trouble h CD IIII& conVCf3.H lOns when there's
background nOise, such as at a party! Docs your family
complam that you arc speakmg too loudly when you feci you
Me speakmg in normal tones! Do members of your famil y
seem to be mumblms or slurnng their words, making th~m
difficult to understand!
If you have experienced any of the above. It IS quite possIble
that yOli arc suffering from a heanng loss and need to sec a
doctor, preferabl y an otologIst or otolaryngologist (car speclal­
Istl·
Most deafness today IS caused by exposure to excessive
nOise. The human caf IS a very del icate Instrument.
The ear
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of sound power that vanes from a to 194-the lowest to the
highesl sound levels that can occur. It can be measured,
accorellOg to the (requency of the sound, by several ddferent
formulas, or "scales" as they arc known. The "A" scale most
nearly IIpprOXI013teS the frequency response of the human car
and IS therefore used for most standards. Decibels measured
on the" A" scal e- slow response arc generally deSignated dBA.
The deCibel scal e IS II logarithmic scale, so that any in e rca~c
of 10 deCibels means the sound has increased \0 times. Thus,
70 dBA IS tcn times as loud as 60 dBA, and 94 dBA IS 100 1\0
x \01 times as loud as 74 dBA. In general, an mcrease of 3
dBA means the sound level has dvubled so that 83 dnA 18
twice as loud as 80 dBA.
While most standards in Canada and the U.S. prohibit
exposure above 90 dBA for an eight-hour period, or above liS
dnA for tllllCS as short as IS rrunutes, experts have for years
mdlcated that exposure to above 85 dBA for any length of time
can be damaglllg. Exposure above 100-11 5 dBA can cause
permanent damnge even though the exposure IS for a short
time.
AmpltAed rock musIc IS often III thiS liS dBA range, as IS
a car hom. A let plane at the ramp produces approximately
120 dBA, and on takeoff thiS mcrcases to the VIClOlly of 14$­
ISO elRA.
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SUluld IS caused by Vibrations. Any sound, whether from a
violin smng that has been plucked or a piece of metal that
has been struck by a hammer, on glnates as a vibration. These
Vibrations compress and expand the all particles nexi !O them
very r3pldly. These air parlld(" movements spread as " waves"
through the surroundlllg au. These waves arc similar to those
caused by a stone thrown III stili water, III that they cominue
outward from the source III all directions, unless deflected,
and they gradually decreasc III IIltenstty as they travel.
Upon stnkmg the human car, the Vibrations arc transmuted
by the uny bones m the middle ear !O the cochlea, or mner
car. This deilcate organ IS filled with flUId and thousands of
tiny hairS. As the vlbr:1t IOnS from the middle ca r arc transmitted
to thiS flUid, the tiny hairS Vibrate, and transmit signals through
nerves to the bram. If these tiny hlurs arc caused to wave tOO
far or tOO much, they can become damaged, causmg heanng
loss. 1111s loss IS noticeably worse m the first hour or twO of
exposure than thel(~ after . Durmg thiS lime the tiny h:urs III
the cochlea become fa tigued, and while they may recover If
not exposed to excessive nOise for 24 hours, they ma y be
permanently dnmaged If the exposure continues.
Unfonun:ltely, mlmy times our cars MC cxposed to damagmg
sounds. Our youth wear stereo headsets, have stereos m their
rooms or attend rock eoncens where sound levels are ohen
dangerous. Many lob sites or work activities expose us to
excessive noise.
Sound h::vcls are measured by deCibel s. The decibel IS a Ulllt
WHAT CAN OUR SAFETY COM.MITTEES DO TO
PR EVENT HEARING LOSS FROM EXCESSIVE NOISE!
Committees should urge special meetings with employers
on cnglllecnng controls to reduce the noise level at the
workplace. Many times Sim ple measures will accomplish great
r edllr.. ll o n .~. Remember, a 20-dBA reduction means that 99
percent of the noise was eliminated (1/10 x VIII: 1/ 100 or I
percent of the nOise IS left1. Every possible effort should be
made 10 get the level to 80 dBA or less.
Committees should inSist on hearing prOteClion If the level
IS not reduced to below 85 dBA.
Whtle the IBEW fecls thllt earplugs or eannuffs are not
adequate protection, and that noise should be engmeered out
of the workplace, there may be occasions where such protecuve
equipment becomes necessary. Sdon: using such eqUipment,
howevcr, the worker needs to be tralOed not only 10 the proper
fitting and wearing of the protectors, but also In proper methods
of malOtalOlOg It. Earmuffs, while prOViding a maximum
u:Juetlon of 3O-JS deCibels when properly adjusted and fitted,
may only give a 10-dBA reduction if their seal IS broken by
hair or eyeglass temples or by sweat. In addition, they are
uncomfortable 11\ hot places and may cause headaches from -,
pre5Sure on the head F..1rplugs can reduce nOise reaching the
middle car by 1$-20 deCibels) however, they mUSt be md,vldualJy
fitted to have any appreciable effect. No twO car canals
arc the same shape or Size. Earplugs are easily lost and difficult
to keep clean. They can cause car infections or irntation and
can onl y be worn m healthy car canals. Sweat and physlC-.11
activity can cause leakage, makmg them less effective. Still,
until we succeed In getting the engineenng controls necessary,
these so-called protective deVices :tre better than allowing lh e
nOise to destroy our heanng!
"
22 I lBEW JOURNAL I JULY 1964