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SOUND
Vibration commonly found in
daily life. Vibration pendulum wall clock, a plucked guitar string, and vocal
cords vibrate to cause noise, are some examples of objects that perform
vibration. Vibration is a back and forth motion events experienced by an object
on a regular basis at the point of equilibrium. Vibration occurs repeatedly on
a regular basis, so it is often referred to as periodic motion. Furthest
deviation is called the amplitude. At point A or point C objects will stop
shortly before moving again. Examples of amplitude is the distance BA or
distance BC. Distance from the point of equilibrium at some point called the
deviation. waves are propagating vibrations that propagate or harassment, while the single vibrations
that propagate called pulse. Wave propagation, require a medium are called
mechanical waves, while propagating through a vacuum or without a medium called
electromagnetic waves. Examples of mechanical waves are sound waves, and the
example of electromagnetic waves are light and radio
waves.
Sound
is a longitudinal wave which spreads in the form of compression and
rarefaction, with spreading direction equals to its vibration
direction. While several properties of sound among other are sound wave
produced by vibrating object, sound wave need medium to spread, and sound wave
can spread in Solid, Liquid, and Gas.
In discussing the topic of
sound waves, it must first be known to the general properties of the sound
waves are
a. Sound waves require a medium
in propagation
Because the sound wave is a
mechanical wave, then the sound propagation requires a medium. This can be
evidenced when two astronauts are far from Earth and the state of the vacuum
created in the plane, the astronauts can not converse directly but use
communication tools such as telephones. Although the two astronauts are in one
plane.
b.
Sound waves undergo reflection ( reflection )
One of the properties that
could be reflected wave is a sound wave can also experience this. Legal wave
reflection : angle of incidence = angle of reflection also apply to sound waves.
It can be proved that the reflection of sound in an enclosed space can cause
reverberations. That is partly reflected sound along with the original sound of
the original sound so that the sound is not clear. To avoid the echo in the
cinema, radio and television studios, and music concert hall sound dampening
walls are lined substances which are usually made of woolen cloth, cotton,
glass, rubber, or
iron.
c.
Sound waves undergo refraction ( refraction )
One of the properties of wave
refraction is experiencing. Refraction events in everyday life, for example at
night the sound of thunder sounded louder than during the day. This is because
during the day the air is cooler than the upper layer of the bottom layer of.
Due to the rapid propagation of sound in cold temperatures less than the
temperature of the hot layer of air above the speed of sound is smaller than
the layer of down, which resulted in the top layer of denser medium than medium
undercoat. The opposite happens at night. So during the day the sound of
lightning propagates from the upper air layer below the air kelapisan. For more
details of this case can you see in the image below.
d.
Sound waves undergo flexing ( diffraction )
Sound waves are very
susceptible to diffraction as sound waves in air has a wavelength in the range
of centimeters to several meters. As we know, that the longer wavelength will
be diffracted easier. Diffraction events occur for example when we can hear the
sound of the engine mobilditikungan road although we have not seen the car
because it was blocked by tall buildings alongside a bend.
e.
Experience a blend of sound waves ( interference )
Experiencing symptoms of a
blend of sound waves or wave interference, which can be divided into two
general categories strengthening constructive interference or destructive
interference or noise and sound attenuation. For example, when we 're between
two loud- speakers with frequency and amplitude of the same or almost the same,
we will hear a loud noise and weak alternately.
For more clearly about sound transmission, please check this video :)
For more clearly about sound transmission, please check this video :)
Most of the sound is a
combination of various signals, but the pure sound could theoretically be
explained by the oscillation speed or frequency is measured in Hertz (Hz) and
amplitude or loudness of the sound measurement in decibels. Sound can
be formatted if there are
the sound source, medium, and listener. The sound will be
reflected if the surface of a hard object, if the object
is soft, the
sound will be absorbed. The laws of reflection of sound are
a. The sound comes, the normal
line, and reflected sound lies in one plane, and the three intersecting at one
point.
b. Reflection angle the same
as an angle of incidence.
Reflected sound can be
divided into 3 kinds:
a.
Strengthen the reflected sound is reflected sound original
sound that can amplify the original sound. It usually occurs in circumstances
between the sound source and the reflective wall is not so far away (less than
10 meters)
b.
Echoes are reflected sound that sounded almost simultaneously
with the original sound. Usually occurs at a distance of between 10 to 20
meters.
c.
The echo is reflected sound is heard after the original
sound. Usually occurs at a distance of more than 20 meters
By the frequency of sound, it
can divided into
three kinds:
1. Infrasound
is sound frequency less than 20 Hz.
2.
Audiosonic
is sound whose frequency is between 20
Hz to 20 kHz.
3.
Ultrasonic
Is sound frequency is more than 20 kHz. The example that can hear the ultrasonic are dolphins and bats. The using
of ultrasonic sound are:
a. Glasses blind, equipped with
ultrasonic sender and receiver utilizing ultrasonic transmission and reception.
b. Measure the depth of the sea, to determine the depth of the sea
c. Medical devices, for example in ultrasound (ultrasound).
e. Measure the thickness of the metal plate
f. Measure the depth of the sea
g. Knowing the position of schools of fish in the sea.
h. Knowing pockets petroleum basin by sending sound waves
into the ground
Sonar (Sound, Navigation, and
Ranging) is used
to determine the propagation of sound in water. How it works is by sending
sonar sound waves under the surface and then wait for the wave reflection
(echo). Sonar is classified into 2 types. Namely passive sonar and active
sonar. Passive sonar is a sonar that cannot send the signal back out. While
active sonar is a sonar that can give a signal and can send it back.
