1. What do you know about sound?

2. Sound Energy Sound is a form of energy.
It is either mechanical or kinetic energy.
It is produced and transmitted by vibrations.
Sound can only occur in waves of vibrating matter.
Sound has 3 requirements: a vibration, a receiver, and a medium.

3. Sound Wave

4. Sound Waves
Sound waves are disturbances moving through a medium such as a solid, liquid, or gas.
Frequency of sound is the number of vibrations in a given unit of time.
Pitch is determined by the frequency of a vibrating object. It is the highness or lowness of sound.
A wavelength of sound is the distance between 2 compressions.

5. Sound Wave

6. Sound Waves
Compression Wave: Sound is called a compression wave because the vibrations move in the same direction as the motion and speed of the wave. Like a slinky.
Sound travels worst through gases and best through solids because of how closely packed the molecules are.

7. Sound Wave Models

8. How do we measure sound? Sound is measured by its vibrations.
We know that frequency, which is related to pitch, of sound is measured by hertz.
We know that the loudness or volume is measured by decibels and is determined by the wavelength.
A wavelength is the distance from a point on one wave to the same point on the next.
A crest is the highest point of the wave.
The trough is the lowest point of the wave.

9. Dou you know the decibel levels of everyday sounds?
10 db is normal breathing
30db is a whisper
55db is normal conversation
90db is a lawnmower
120db is a rock concert
140db is a jet engine on a airplane
*Listening to sounds with high decibels for long periods of time without ear protection will cause hearing loss!

10. Sound can be manipulated!
To amplify sound or the amplification of sound is the process of making sound louder.
The amount of energy carried by a sound wave is measured by decibels according to the compression of the wave.
Resonance changes sound according to the sound quality. 2 sounds can have the same frequency and amplitude, but sound very different.

11. Sound and Musical Instruments
String Instruments: plucking or strumming strings and causing a vibration. (violin or cello)
Brass or Woodwind Instruments: Blowing air through a column to vibrate a reed. (trumpet or clarinet)
Percussion Instruments: Striking or hitting to cause a vibration. (drums, triangle)

12. Musical Instruments

13. Musical Instruments
Instruments with a long column will usually have a low pitch.
Instruments with a short column will tend to have a high pitch.

14. Sound Travels
Sound travels better in warm thick air than cold thin air.
Sound needs vibrations to travel. Can sound travel if no molecules of matter are present?
Morse Code is a method developed by Samuel Morse to communicate over long distances via the telegraph machine. It uses a series of taps to represent letters.

15. Telegraph Machine

16. Morse Code

17. Sound and Animals
Humans and animals both hear sound, but they do hear it in different ways.
Animals hear sound at a higher frequency than humans.
They hear sounds beyond human range.
Animals hear sound through their ears, but also hear it in other ways. Do you know any?

18. Sound and Animals
Dogs hear sound like humans through their ears, but they hear sounds at a much higher frequency.
Whales use sonar to hear sound.
Sonar is a system that sends out sound waves to determine the depth of a body of water. The sound bounces of the object and is collected by the receiver, which is converted into a picture for the animal.

19. Sonar

20. Sonar

21. Sound and Animals Bats hear sound through echolocation.
Echolocation is a system that sends out sound waves into the air. The sound waves bounce off the object and are collected by the receiver, which converts the sound data into a picture. The difference between echolocation and sonar is that sonar takes place underwater and echolocation takes place in the air.

22. Echolocation