SOUND

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 :)

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.