The Washington times., 1920-10-16
SOME FACTS ABOUT
NOISES IN YOUR CAR
Continuous Sounds May Pro-
duce Pleasant Sensation.
Some Can't Be Detected.

Noise is sound OF any sort, says
Webster, whether II Is pleasant or un-
pleasant, agreeable or disasreeable.
In an automobile IL IL apt TO be dis
agreeable, writes Joseph w. Williams
In Motor IL is a strange fact thst
practically the same twitter which Is
admired IN canary 10 abhored In q
Windshield. The fact Is that automo-
biles are judged more by their silence
than by any other quality and that is
why manufacturers In making their
cars, and careful automobile users In
maintaining them, strive TO keep the
quality OF noise as far removed from
their vehicles as possible.
The variety OF sounds which can be
produced by an automobile not In the
hest OF repair is bewildering. We have
about every range from the dull thud
OF q loose main bearing to the shrlli
sQueal OF q rusty spring. or from the
clink characteristics Of the heavy car
bon deposit 10 the thud due TO loose
body bolts or other retainers holding
heavy parts OF the structure In place.
FINALLY GROWS PLEASANT.
1t Is a fact that the more contin-
uous sounds are the less unpleasant
they are likely to be. For this reason
II Is a fact that the sounds which
come from reciprocsting parts are as
rule more unpleasant than those
which come from rotating parts. A
continuous hum, for instance, In
rear axle 10 not nearly as unpleasant
as the intermittent knock, due TO
loose connecting rod bearing. The
fact, however, that these different
units make different sounds, make IL
possible for the experienced ear 10
almost invariably judge the point
from which the sound proceeds ana
an experienced, motor-wise mechanic
can very often tell at the first In
dication Of sound just what point he
should reach in making his repair.
The human ear is only capable OF
detecting sounds within certain
ranges. That is, all sound Is due TO
vibration. This vibration might be
set up by impact. such as in loose
bearing, or in a spark which Is too
far advanced. or II might be set up
by friction, such as in rusty. unoiled
spring. Nevertheless, the effect OF
noise on the ear is created by these
vibrations, which, In turn, set up
sound waves. The sound waves are
transmitted through the air, which Is
an elastic medium. Sound can only
be transmitted through elastic me
diums. For instance, If an electric
bell were operated in vacuum 1t
would not be heard because there
would be no elastic medium in which
to form and transmit the impulses.
These sound vibrations are known as
waves and II takes these waves an
appreciable length of time to travel
from one point to another. Through
the air, it has been found that sound
has a velocity of about Lib feet per
second II has been found that this
velocity is practically Independent of
the pitch of the sound, or the length
of the sound wave. A very interest
ing example of this is, of course, in
the instance where the bullet from
explosion of the gun. the projectile
reaching the target before the sound.
DIFFERENCES IN SOUNDS.
Noises or sounds differ from one
another in loudness. pitch and quail
ity, Loudness Is the amount of the
sound, pitch Is highness or lowness OF
tone and the quality is the character
OF sound: that is, a man may sing a
note at the same pitch and with the
same loudness of a piano note. but the
quality will be different; that is, its
determining characteristic. In the
same way, a sound of the same pitch
and loudness may proceed from some
part Of an automobile, but the quality
OF that sound may determine the point
from which IT proceeds.
One OF the very interesting facts
about sound is that below a certain
point and above a certain point the
human ear cannot hear It, These
limits are not fixed, but vary for diff
ferent individuals. For instance, If
the impulses in the air caused by
sound vibration follow each other less