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Sound, so vital a part of our existence,
is growing to such disagreeable pro-
portions within our environment that to-
day it is a very real threat to our health.
So noisy, in fact, is America's urban
environment that people living in con-
gested sections of large cities may be
hearing far less than they realize; many
are developing severe hearing loss. Sub-
urbanites will not fare much better. As
noise levels in their communities con-
tinue to increase, they may be destined
for the same fate.
The problem is not limited to the
out-of-doors. Noise in our homes is
beginning to reach harmful levels. We
are using more tools and appliances and,
as their power has increased, so has the
noise. The combination of hi-fi equip-
ment and the rock music which domi-
nated the past decade, alone has prob-
ably affected the hearing of a whole
generation of listeners.
If these statements seem scary, they
should. They are not exaggerations.
Noise pollution is a growing menace,
not just to boilermakers and jackham-
mer operators, but to all of us. The
noise level we experience daily has
increased so gradually that we fail to
recognize its danger. But noise is a
danger. It can result in a hearing loss
that not only can be a handicap, but
what is worse, a hearing loss that can-
not be restored.
Unless controlled, noise pollution
will exact an increasingly heavy toll on
society. Already an estimated 16 million
people in the United States suffer from
some degree of hearing loss directly
caused by noise. Such hearing loss, in
fact, is a major cause of industrial in-
jury. Compensation to its victims an-
nually runs into millions of dollars.
Although definitive research has yet
to be done, some recent studies suggest
that existing noise levels may be a
cause in the rising rates of heart disease,
ulcers and mental illness and may even
adversely affect the unborn child.
The danger from noise is very real.
u.s. environmental protection agency
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Sound moves through the air some-
what like waves move in the ocean.
In sound, the waves are alternate rings of
compressed, and then rarefied air mov-
ing away from a central source at a
constant speed. As each wave—first a
compression, then a rarefaction—en-
counters an object, it exerts a force—
a push, then a pull—on the object. This
is why sound can break a glass or cause
a window screen to vibrate.
For humans, sound has two significant
characteristics: pitch and loudness. In
terms of affecting people, pitch is gen-
erally an annoyance—the sound of chalk
scraped over a blackboard surface. Pitch
is the height or depth of a tone or
sound depending on the relative rapidity
of the vibrations by which it is pro-
duced. In low-pitched sounds, the vibra-
tions are relatively far apart. In high-
pitched sounds, they are squeezed closer
together.
Loudness, on the other hand, can
affect our ability to hear. It is the inten-
sity of the sound waves combined with
the reception characteristics of the ear.
The intensity of a sound wave may be
compared with the height of an ocean
wave. In terms of sound's affect, this
intensity is how hard a sound wave hits
an object, a characteristic which can be
measured precisely with instruments.
But the loudness heard by a human ear
is slightly different from the purely
physical values. Our ears hear sound
at intermediate frequencies better than
sound at very low or very high fre-
quencies.
Sound is measured by decibels. The
2ero on the decibel scale is based on
the lowest sound level that the healthy,
unimpaired human ear can detect.
Decibels are not linear units like
miles or pounds. Rather, they are rep-
resentative points on a sharply rising
curve. Thus, while 10 decibels is 10
times more intense than one decibel,
20 decibels is 100 times more intense
(10 x 10), 30 decibels is 1,000 times
more intense (10 x 10 x 10) and so
on. One hundred decibels, therefore, is
10 billion times as intense (that is,
represents 10 billion times as much
acoustic energy) as one decibel. The
reason for such a complicated scale is
simply that the human ear detects a
wide range of acoustic energy.
Sound levels are measured at their
source; thus their decibel rating de-
creases as the distance from that source
increases. These ratings should, there-
fore, be regarded as averages and should
be used primarily for comparative pur-
poses.
The gentle rustle of leaves, for ex-
ample, is rated at 10 decibels, while a
typical office has about 50 decibels of
background noise. Moderate traffic noise
ranges around 70 decibels; a police
whistle hits 80. Subways and elevated
trains rank just below thunder at 100
decibels. At just above 120 decibels the
ear begins to feel pain.
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Pain occurs as the ear unsuccessfully
attempts to protect itself through
a mechanism physicians call "the acous-
tic reflex." When sound enters the ear,
the waves pass through the ear canal
to the eardrum which vibrates. The ear-
drum conducts these vibrations to three
tiny bones called ossicles — the three
tiniest bones in the body. It is here
that the acoustic reflex occurs. The
ossicles change the loudness of sound
before it enters the inner ear. Normal
action of the ossicles may amplify soft
sounds or dampen loud sounds as their
tiny muscles contract to decrease the
pressure of the sound waves.
The acoustic reflex protects the inner
ear from extra loud sounds by reducing
them, just as the eye protects itself from
extra bright light by contracting the
pupil. The ear is not completely suc-
cessful in this task. The reason is two-
fold: first, the reflex occurs on command
from the brain a few hundredths of a
second after the loud sound is first
sensed. Thus, at least some of the sound
at full loudness gets through to the
delicate inner ear before the reflex goes
into operation. Second, muscles cannot
contract indefinitely so their sound-
dampening capacity is limited. Thus, if
the loud sound is sustained, the inner
ear may still be bombarded with exces-
sive sound pressure even after the reflex
has had a chance to work. In the case
of impulse sounds such as a gunshot, the
reflex is virtually useless as a defense.
What happens when loud sounds
enter the inner ear? The ossicles trans-
mit the vibrations to a fluid contained
in a tiny, snail-shaped structure called
the cochlea. Within the cochlea are
microscopic hair cells that move back
and forth in response to the sound
waves just as seaweed on the ocean floor
undulates in response to wave action in
the ocean. It is the energy impulses
created by the movement of these crucial
hair cells that go to the brain where
they are interpreted as sound. But just
as the seaweed can be torn and ripped
by violent wave action in the ocean, so
too, can hair cells be damaged by too
intense sound waves.
damage to hearing
When intense sound waves occur
only briefly, the damage may be tem-
porary. But if loud noises are frequent
or sustained, the damage may be per-
manent, and such noise-induced hearing
loss cannot be restored either through
surgical procedures or hearing aids.
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Sound Levels and Human Response
Conversational
Relationships
Hearing
Effects
Carrier Deck
Jet Operation
Jet Takeoff
(200 feet)
Discotheque
Auto Horn (3 feet)
Riveting Machine
Jet Takeoff
(2,000 feet)
Garbage Truck
N.Y, Subway
Station
Heavy Truck
(50 feet)
Pneumatic Dn
(50 feet)
Alarm Clock
Freight Train
(50 feet)
Freeway Traffic
(50 feet)
Vary loud
Conversation, % ft.
Loud
Conversation, 2 ft.
Telephone Use
Difficult
Loud
Conversation, 4 ft
Air Conditioning
Unit (20 feet)
Normal
Conversation, 12 ft.
Light Auto Traffic
(100 feet)
Living Room
Soft Whisper
(15 feet)
Broadcasting
Studio
Threshold of
Hearing
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Permanent loss, however, occurs only
in certain frequencies because different
hair cells respond differently to various
frequencies. Unfortunately, the hair cells
that seem to be the most susceptible
to damage are those that respond to the
high frequency.
This selective damage can severely
impair the understanding of human
speech. It may be even more insidious
than a broad-range hearing loss because
it may not be readily recognized. Recent
studies of young school children, thought
to be "slow learners" revealed that at
least some of them simply could not
hear everything that was being said in
the classroom. Once adjustments were
made, these children were able to match
the scholastic performance of their class-
mates. Similar undetected hearing diffi-
culties may be the cause of unexplained
performance impairment among adults.
Obviously, noise may accelerate the
progressive loss of hearing we all suffer
as we grow older. To learn just how
much, scientists visited an isolated area
in Africa to examine the hearing acuity
of a large number of elderly tribesmen
and their youthful counterparts. Their
findings: men in their 70s and 80s had
hearing sensitivity nearly equal to that
of the young boys and equivalent to
that of Americans 30 to 40 years their
junior!
Undetected hearing loss is a clear
danger to each of us. We are dependent
on a wide variety of audible signals,
many of them for our safety. Consider
the danger to a driver or pedestrian who
cannot hear the siren of a fire engine,
or the construction worker who does
not hear the warning whistle before an
explosive charge is detonated.
other physical effects
Selective hearing loss, however, is
only one of the ways excessive noise
takes its toll. At sound levels above
35-45 decibels, noise disturbs a sleeping
person. At levels above 50-60, it dis-
turbs conversation. All across this range
people experience annoyance and dis-
ruption of their activities. And at levels
of 85 decibels or above, stress reactions
can be expected.
When the brain perceives noise, it
reacts. Most of us automatically interpret
unexpected noise as danger, a signal to
prepare to fight or run. It may be a
subconscious reaction, but it is clearly
indicated by the physical changes that
take place in response to noise. Even
a sound of moderate volume and short
duration such as a heavy truck passing
on the other side of the street (rated
about 80 decibels), produces a remark-
able number of these physical changes.
Blood vessels in the brain dilate while
blood vessels in other parts of the body
constrict. Blood pressure rises, and the
heart rhythm changes. The pupils of
the eyes dilate. The blood cholesterol
level rises. Various endocrine glands
pour additional hormones into the blood.
Even the stomach changes its rate of
acid secretion. While most of these re-
actions are only temporary, the modern
environment presents such ever-chang-
ing noise levels that some of these
"temporary" effects become chronic.
We may not be immediately aware
of these changes since they are functions
of the so-called involuntary or automatic
nervous system. Yet this dramatic re-
action to noise occurs in our bodies
many times each day as we encounter
the clamor of modern Twentieth-century
living. Traffic, machinery, household ap-
pliances, lawnmowers, telephones, type-
writers, barking dogs and shouting peo-
ple all contribute. The effect on each
of us can be profound.
Ulcers, indigestion, "heartburn", gas-
tro-intestinal malfunctions, heart disease,
all are connected to stress in general
and since noise is interpreted by the
body as a stress, noise may also be a
contributing factor in the rate of oc-
currence of these disease conditions.
psychological effects
Stress also is a factor in mental ill-
ness, which may be defined as a reaction
to a person's inability to cope with the
many tensions of daily living. Mental
illness develops when individuals are
literally overwhelmed by the onslaught
of stress and mentally retreat to escape.
While environmental noise alone prob-
ably does not produce mental illness,
the continual bombardment of noise on
an already depressed person cannot be
helpful. Certainly it interferes with
sleep, producing irritability and other
tensions. Definitive research has not
been done in this area, but one 1969
study in England provides strong sup-
porting evidence. Comparative studies
of persons living adjacent to London's
Heathrow Airport with others living in
a quieter environment revealed that
among those living in the noisy environ-
ment there was a significantly higher
rate of admission to mental hospitals.
Another recent medical discovery is
the effect of noise on unborn babies.
Previously they were thought to be in-
sulated from the noise stress of the out-
side world, but now physicians believe
that external noises can and do trigger
changes in fetuses.
Even when we do not suffer from
these extreme and tragic consequences,
we are victims of noise. It is well known
that noise causes headaches in a variety
of ways. Because the brain interprets
it as a danger signal, noise interrupts
thought and mental concentration. This,
in turn, not only lowers the working
efficiency of people doing exacting or
predominantly mental work, but the
constant distraction of noise makes them
more nervous, irritable and generally
unsettled. It affects others in a similar
manner. One study of steelworkers in-
dicates that those working in a noisy
environment are more agressive, dis-
trustful and irritable than workers in
a quieter environment.
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Ocientists now tend to agree that the
^ noise level for potential hearing
loss begins at about 70 decibels. Some
of them are deeply concerned because
our normal daily life regularly exposes
us to noise levels of about 70 decibels
even inside our homes.
The kitchen is usually the noisiest
room in the house. The combination
of garbage disposals, mixers, blenders,
dishwashers and non-sound-absorbent
walls can drive the kitchen din up to
the 80 to 90 decibel range, equivalent
to the noise level right outside a major
jetport. In the living room, the vacuum
cleaner may put out 80 decibels; the
television set, 70-80 and, if there is a
hi-fi in the house, the levels can run
upwards of 100. Outside in traffic, 70
decibels is a typical level; cars, trucks
roar along at some 90 to 100 decibels
with motorcycles topping the noise pa-
rade at more than 100.
At work, a noisy office can approach
50 decibels; a busy factory can average
85; a print shop, 95; a construction site,
100; a riveting shop, 110; a boiler
factory, 118; a lumbering site, 125 and
a jet runway, 130.
spreading pattern
Cities have always been noisy, but
noise is now spreading to areas that
were relatively quiet just a few years
ago. Noise levels in average communi-
ties are now running at about 70 deci-
bels and up.
Clearly, something must be done soon
or we will seriously and permanently
maim our population with pure noise.
Fortunately, the knowledge and tech-
nology to control noise already exist.
As a matter of fact, this is one instance
where the knowledge of control tech-
niques exceeds the knowledge about
the effects on human life and on the
environment.
We have two practical means for
control: (1) reduction of noise at its
source such as making the sound-pro-
ducer quieter and (2) alteration of the
sound path by distance or by shielding,
such as building better walls between
apartments.
The second approach is being used
more frequently today as people become
more aware of the annoyance of noise.
New building codes require better sound
insulation in homes and apartments.
More and more communities are adopt-
ing zoning ordinances that attempt to
segregate noisy factories or airports from
residential areas. Sound-absorbent ma-
terials and construction designed to
intercept sound paths are slowly coming
into wider use in offices and homes.
New highways are being constructed in
below-grade "cuts" so as to redirect traffic
noise up and away from adjacent areas.
Aircraft increasingly are being required
to use reduced-power, noise-abatement
maneuvers around airports.
There are many examples of available
noise control technology that are not
being utilized. More flexible building
codes would permit the use of quieter
kinds of plumbing pipes. Sound-absorb-
ing, vibration-damping materials can
curtail the noise of motors and engines.
Power generators can be quieted with
baffles, exhaust silencers and sound-ab-
sorbers. Truck tires can be made with
quieter treads. The list goes on and on.
In many cases, the cost of building
quieter machines is the same or only
slightly higher than that of the current
noisy ones. Even though the new equip-
ment may cost more, it can prove more
profitable in the long run. The jumbo
jets, for example, are quieter than the
older ones, yet they are more powerful
and carry twice as many passengers.
All of these methods are only partial
measures as noise levels continue to
rise. Most specialists in the field agree
that much of the solution must come
from eliminating some of the noise at
its source.
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The key is attacking noise pollution in
the design stage. It is much easier
to design noise out of a machine before
it is built than to absorb or deaden the
noise afterwards.
If noise is relatively easy to eliminate,
why has it not been done?
Why has our environment become so
noisy?
The answer is that we have permitted
it. In fact, in some situations the Amer-
ican public actually asks for more noise.
How? One example is the problem a
power lawnmower manufacturer ran in-
to when he designed and marketed a
substantially quieter mower. Sales were
poor and to add to the problem, pur-
chasers began returning the mowers,
complaining that they were "under-
powered." The mowers were, in fact
just as powerful as competing mowers,
but too many Americans equate noise
with power—"the noisier it is, the more
powerful it must be." Since this mower
was so quiet, they concluded, it had to
be underpowered. The same psychology
applies when people customize or "hop
up" their automobiles. One of the most
popular changes is a modification of
the original exhaust system with special
mufflers and echo chambers that sharply
increase the exhaust noise.
Another peculiarity in human psy-
chology and noise is the use of con-
struction machinery in urban environ-
ments. Some of this equipment puts
out noise in excess of 120 decibels—
almost at the pain threshold. But oddly
enough, it elicits few complaints. Why?
Psychologists explain that people tend
to tolerate these noisy intrusions be-
cause of their "temporary" nature. Sub-
consciously, they tell themselves that
this insult will soon go away. The fault
in this thinking is that, at the typical
rate of urban construction and redevel-
opment, one project usually follows an-
other and one temporary annoyance
after another adds up to a permanent
noise fixture. Construction, of course,
could be halted, but a more practical
alternative would be to quiet equipment
and perhaps regulate the hours that it
can be operated.
This alternative and similar ones,
however, will not be pursued until the
public demands it. Since both govern-
ment and industry respond only to
public demands, the only real solution
to the overall noise problem is a rising
public awareness of the dangers of noise
and a demand for quiet. Only when
the public expresses a preference for
quieter machines, will industry begin
to compete on the basis of how quiet
their machines can be built. What can
we do about it?
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One of the first steps which the pub-
lic can take towards quieting the
environment is to make "noise" about
noise. No laws will be passed, no regu-
lations promulgated, no standards set
unless the public wants them and lets
its elected officials know it.
As part of that public, don't under-
estimate the influence you, as an indi-
vidual, can have in effecting change.
Not long ago, a mild little old lady
walked firmly out to the street and
right up to the foreman of a crew
which was ripping up her street with
ear-hurting jackhammers. The noise,
she told him, was unbearable and was
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disturbing everyone on the block. The
foreman turned to his crew and told
them to pack up and leave. His instruc-
tions, he explained, were to keep work-
ing until someone on the block com-
plained.
In London, a noise-battered citizen
finally had enough and began the Noise
Abatement League which later convinced
the Queen to set up a royal commission
to look into Great Britain's noise prob-
lems. As a result, that nation now has
a Noise Abatement Act.
When the Sixth Avenue subway was
noisily being constructed some irritated
New Yorkers banded together to form
the Citizens for a Quieter City, Inc. The
group succeeded in getting the mayor
to set up a Task Force on Noise Control
which recommended specific changes in
the city's noise ordinance.
In Chicago, Citizens Against Noise
(CAN) persuaded the City Council to
pass the effective 1971 anti-noise ordi-
nance. CAN then expanded its activities
to help other noise-bothered citizens
throughout the country.
In Boston, a physicist was so bothered
by sonic booms that he gathered some
fellow sufferers and started the Citizens
League Against the Sonic Boom which
exposed this as a threat from supersonic
transports.
It is the American way of life for
citizens to petition government for the
redress of grievances. Certainly noise is
a grievance, and for relief you can
petition government at the appropriate
levels. You also can join with other
citizens and complain as an organization
—many voices are always louder than
one.
The Federal government responded
to the public's early efforts for less
noise by establishing the Office of Noise
Abatement and Control in the Environ-
mental Protection Agency. This Agency
has the responsibility for determining
the extent of noise pollution problems
and for establishing standards for con-
trol measures.
To help build public awareness and
to help individuals express their prefer-
ences, products soon will be labeled as
to the levels of noise they generate when
in use. Limitations will also be set on
the maximum amount of noise some
types of products—such as construction,
transportation and other equipment
powered by the internal combustion
engine—may generate.
steps to take
It is the state and local governments
which have the responsibility to take
the steps necessary to create a quieter
environment. Since petitions or com-
plaints are much more effective if you
have all the facts, first make sure you
have the correct official or agency to
whom they should be sent. Just locating
someone who will admit responsibility
for making things quieter may be a
problem since noise control has not yet
become a high priority environmental
issue in many places.
A next step is to examine local laws
and regulations. It may be, for example,
that a city ordinance already exists
which requires a motor vehicle to have
a "muffler in good working order." Such
laws have been on the books since the
advent of the automobile. More effective
laws—such as Chicago has—state spe-
cific decibel limits for noise, just as
speed laws limit the miles-per-hour for
vehicles.
The problem with many "muffler
laws" and nuisance regulations, how-
ever, is that they are so vague they are
practically unenforceable and, pending
enactment of a workable legal scheme,
the best alternative for citizens to get
relief may be by a legal suit. For in-
stance, a worker who loses his hearing
on a noisy job may sue his employer
for compensation. Every city has a
building code. The better ones (such
as New York's) specify limits of the
noise which walls and floors may trans-
mit. If your home or office is bothered
by noise from a neighbor, you should
investigate, it may be that a building
code provision has been violated.
You may not have to fight a legal
battle alone. Today, a growing number
of public interest law firms specialize
in environmental issues. University law
students, while not able to represent
you in court, can be helpful in preparing
your case.
The press, radio and television also
can be good allies. A letter to the editor
can sometimes accomplish more than a
petition with a thousand signatures. Be
sure your case is well presented, how-
ever, or you may set back the cause by
being considered just a "crank."
Finally, as a quiet-loving citizen, you
have a responsibility not to offend your
neighbors and fellow man with your
own noise. You can quiet your home
with drapes or wall hangings, carpets,
acoustic tile and soft furniture. You
can listen to your stereo on a headset
instead of blasting everyone with power-
ful wall speakers. You can replace a
raucous lawnmower with a quiet one
and you can make sure your auto's
muffler is in good shape. You should
appreciate that noise does not mean
power.
You can express your concern for
noise, too, by refusing to buy noisy
appliances. Be sure you tell the sales-
man why you won't buy the appliance,
and write your opinion to the manu-
facturer. By practicing quiet in your
personal life and by making "noise"
about noise, you can help make our
environment less noise-polluted.
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