1. Sound
Sound is a wave
2.1

2. Sound is a type of mechanical wave
A mechanical wave is a wave that travels through a medium.
Sound is a wave that is produced by a vibrating object and travels through matter

3. The disturbances that travel in a sound wave are vibrations
Vibration- a rapid back-and-forth motion
Sound is a longitudinal wave, meaning the medium vibrates back and forth in the same direction as the disturbance

5. How sound waves are produced
Vibrations are required to start sound waves
Your vocal cords within in your larynx (voice box) vibrate to create sound waves

7. How sound waves are detected
The shape of your ear helps collect sound waves
Your outer ear collects sound waves and reflects them back into a tiny tube called the ear canal.

8. The Human Ear

9. How sound waves are detected
At the end of the ear canal is a thin, skin-like membrane stretched tightly over the opening, called the eardrum. When sound waves strike the eardrum, they make it vibrate.

10. How sound waves are detected
The middle ear contains three tiny, connected bones called the hammer, anvil and stirrup. These bones carry vibrations from the eardrum to the inner ear. 

11. The Human Ear

12. How sound waves are detected
One of the main parts of the inner ear, the cochlea, contains about 30,000 hair cells. Each of these cells has tiny hairs on its surface. The hairs bend as a result of vibrations. This movement triggers changes that cause the cell to send electrical signals around nerves to your brain-this allows you to hear sound

13. The Human Ear

14. Sound waves vibrate particles
Let’s think about how a drum works:
When the drum is struck the drum skin vibrates rapidly, it pushes out and then in, over and over again. The nearby particles in the air get pushed by the vibrating drum skin. The particles in the air become bunched together, or compressed.

15. Sound waves vibrate particles
When the drum skin gets pushed the opposite way, a space opens up between the drum’s surface and the particles. The particles rush back in to fill the space.

16. Sound waves vibrate particles
The back-and-forth movement, or vibration, of the particles is the disturbance that travels to the listener. Both the bunched up areas, or the compressions, and the space between the compressions are parts of the wave.

17. Sound waves vibrate particles
The waves consist of repeating patterns of compressions and spaces between the compressions.

18. Sound waves vibrate particles
The compressions are areas of high pressure
The spaces between the compressions are areas of low air pressure
The high- and low-pressure air pushes and pulls on the air around it.
That is how a sound wave travels through the air and transfers kinetic energy from one place to another.

22. SOUND IS A MECHANICAL WAVE
A vacuum is empty space. It does not contain any particles-or very, very, few of them.
Sound is a mechanical wave. It can only move through a medium that is made up of matter. Sound waves cannot travel through a vacuum.

23. SOUND IS A MECHANICAL WAVE
In the middle 1600s, a scientist named Robert Boyle put a ticking clock in a sealed jar and pumped out more and more air (creating a vacuum) until he could not hear the ticking anymore. This demonstrated the sound does not travel though a vacuum.

24. The speed of sound depends on its medium
Sound travels slower than light, and it does not always travel at the same speed in every condition.
Two main factors affect the speed of sound: material that makes up the medium (like air or water) and the temperature.

25. Calculating Speed
To calculate speed for our purposes we will use the formula:
Speed = Distance/Time
We will use this formula when completing our speed of sound activity.

27. The Effect of the Material
Sound travels faster through liquids than it does through gases because a liquid is more dense than gas.

28. The Effect of the Material
This means that the particles are packed closer together. It takes less time for a water particle to push on the water particles around it because the particles are already closer together than the particles in air.
The materials in elastic solids (able to vibrate) are packed even tighter and sound travels even faster

29. The Effect of the Material
Medium
State
Speed of Sound
Air (20 degrees C)
Gas
344 m/s (769 mi/h)
Water (20 degrees C)
Liquid
1,400 m/s (3,130 mi/h)
Steel (20 degrees C)
Solid
5,000 m/s (11,200 mi/h)

30. The Effects of Temperature
Sound travels faster through a medium at higher temperatures than at lower ones.
This is because the particles are moving faster at higher temperatures so they bump into each other faster.

31. The Effects of Temperature
TEMPERATURE AND SOUND SPEEDS
Medium
Temperature
Speed of Sound
Air
0°C (32°F)
331 m/s (741 mi/h)
100°C (212°F)
386 m/s (864 mi/h)