This document discusses the properties of sound. It explains that sound is a type of energy that travels through matter in longitudinal waves of compression and rarefaction. It moves through solids fastest and gases slowest. Echoes are sounds waves that reflect off surfaces. Covering rooms in soft materials helps absorb sound waves and reduce echoes by transferring the wave's energy into thermal energy. Pitch is how high or low a sound is and is related to frequency, or the number of vibrations per second. The Doppler effect changes a sound's pitch depending on whether the source is moving toward or away from the listener. Amplitude refers to the density of compressions and rarefactions in sound waves.

1. What are
the
properties
of sound?
Chapter 12: Lesson 2:

2. Play a guitar.
What do you hear?

3. Sound
Is a type of energy we
hear.

4. Vibrates
Moves quickly back and
forth.

5. Compression
Rarefaction

7. Outer ear
Inner ear
Ear drum
Middle ear

8. Sound Waves
Vibrations that move
through matter

9. Direction of sound
Direction of energy

10. Sound waves moves in the
same direction the energy is
moving in.
Longitudinal
Waves

11. Waves that move in a different
direction.
Transverse
Waves

12. Sounds travel through 3 media.
- Sound travels through the solid the fastest
(energy passed through closely packed particles)
- Sound travels through the gases the
slowest.

13. What is an echo?
Echo are sound waves that are reflected
back.
(When the sound wave hits a flat, firm
surface)

15. How can echo or noise be
reduced?
By covering the room with soft, thick, uneven
material.
Floor foam
Wall padding
Wood panels
Wall art

16. How does covering rooms with the above
materials help?
When a sound wave hits the material the
sound is absorbed (changes to thermal energy).
Absorption:
Transfer of energy when
a wave disappears into a
surface.

17. Frequency
The number of times an object vibrates per
second.
Unit:
Hertz (Hz).

18. Musical notes can be:
High notes
Low notes
Pitch
How high or low sound is.

19. Low pitch
sounds has
lower
frequency.
High pitch
sounds has
higher
frequency.

20. Is there a difference between
pitch and frequency?
YES!!!
Pitch is the way our ears hear sound.
(The way we hear sound is related to the
number of peaks BUT, they are not the
same thing)

21. How to change pitch?
High pitch
Short guitar string
Vibrates fast
causing high pitch

22. Low pitch
Long guitar string
Vibrates slowly
causing low pitch

23. If you are standing still the sound waves will
sound normal

24. If the source of sound is moving towards
you, you will hear more vibrations.
So the sound
you are
hearing
becomes high
pitched.

25. If the source of sound is moving away from
you, you will hear less vibrations.
So the sound you are hearing
becomes low pitched.

26. When sound frequency changes due to
moving towards or away from the sound.
The Doppler
effect.

28. When you are TALKING the sound waves
will look like this
When you are SCREAMING the sound waves
will look like this
When you are WHISPERING the sound
waves will look like this

29. Amplitude
How dense is the air during compressions
and rarefactions.
Units:
Decibels (dB)

30. Humans hearing range.