What Is Sound?

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Sound
A. What is the definition of Sound?
Sound is everything that a person, animal or computer can hear. It can be created in a countless number of ways and occurs from anything as simple as tapping on a table.

All sounds are a series of vibrations that travel through a medium in all possible directions. The cause of sound is the vibration of an object; once the item vibrates the sound waves then radiate outwards until they are either stopped or they die out. A sound wave has three characteristics: Frequency, amplitude and phase. These three allow us to measure pitch, speed and potentially the energy of the wave as well.

Sound travels when particles interact with each other when a sound source effect the first particle of a medium. This then causes the particle to vibrate backwards and forwards which then means that the particle collides with its neighbouring particles causing them to shift in the exact 0.4cm 0.4cm

0.5cm
0.5cm
0.6cm
0.6cm
0.7cm
0.7cm
0.8cm
0.8cm
0.9cm
0.9cm
1cm
1cm
same manner.

The diagram above shows a tuning fork that when struck it sends vibrations outwards towards particles which are then flung backwards and forwards into eachother as the cycle progresses. The measurements show the distance each particle travels when it is hit, this decreases as the wave gets longer because there is less energy travelling through it. The overall result of this the further you are away from the sound source the quiter the sound will be because the energy levels in the wave would have decreased.

During a cycle, a wave will go through two different stages ‘compression’ and ‘rarefaction’. Compression is when a high number of particles are all bunched together almost as a block which means a wave moves freely through the medium however, when this block ends paticles will shoot off the edge in order to find different particles to collide with. This leads them into a more open space where there aren’t as many particles and they are much more spaced apart, which then means a particle needs to use up more energy and the wave then gets even weaker. The diagram below shows two waves (3 cycles per second and 4 cycles per second) and how they change from compression to rarefaction.

Rarefaction
Rarefaction

1 complete cycle
1 complete cycle
Compression
Compression

B. How does sound travel?
Sound travels by vibrations in a medium in the form of waves. These waves are known as ‘mechanical waves’ and they transport energy from one place to another.

When sound travels it has to travel through a medium; a medium is either a gas, a liquid or a solid. All three of these will have a huge effect on how fast the sound will travel.

A vibrating object will cause pressure on any gas particles around it, this causes them to collide and press against each other which then creates a wave that constantly expands away from the object. This wave, is the sound wave that eventually reaches a person’s ear.

In liquid sound travels faster than it does in gases due to the fact that it is denser. This means that there are more particles that are all closer together so they are able to come in contact with each other faster meaning that the actual wave will travel faster as a whole. This same rule applies for solids where sound moves a lot faster than in both gases and liquids because it is so dense.

Sound wave hitting solid particles
Sound wave hitting solid particles
Sound wave hitting liquid particles
Sound wave hitting liquid particles
Sound wave hitting gas particles
Sound wave hitting gas particles

C. What is the speed of sound?
The speed of sound is ultimately the speed one wave of sound travels to get from one point to another. The overall speed of sound will vary depending on a few factors, those are: altitude, temperature and the medium the wave is travelling through.

There is no constant speed that is known as the speed of sound due to the fact that it is...
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