1. PROPERTIES OF SOUND CHAPTER 2, SECTION 2

2. Loudness describes your PERCEPTION of sound.
The loudness of sound depends on 2 factors:
The amount of _ENERGY_ it takes to make the sound
The _DISTANCE__ from the source of the sound.

3. Energy of a Sound Source
The greater the _AMPLITUDE_ of a wave, the more _ENERGY_ the wave has
The larger the _AMPLITUDE_ of the sound wave, The _MORE_ energy it has and the _LOUDER_ the sound.

4. Things with a large amplitude:
Rocket ship
Jet engine
Rock concert
Things with a small amplitude:
Whisper
Soft rain
Slow moving river

6. _LOUDNESS_ increases the closer you are to a sound source.
The closer the sound wave is to its _SOURCE_, the more _ENERGY_ it has in a given area.
Mosquitone sounds

7. If you are close to a speaker it is louder than if you are far way.
As you move away from a sound source, _LOUDNESS_ decreases because intensity _DECREASES_.
Think about it:
If you are close to a speaker it is louder than if you are far way.
Mosquitone sounds

8. Measuring Loudness
The unit to measure loudness is called the ___DECIBELS___.
It is abbreviated as dB.
Mosquitone sounds

9. PITCH
The pitch of a sound is a description of how _HIGH_ or _LOW_ the sound seems.
The pitch of a sound that you hear depends on the __FREQUENCY_ of the sound wave.

10. PITCH A high frequency wave means a high pitch.
A low frequency wave means a low pitch.

11. PITCH AND FREQUENCY
Sound waves with frequencies above the normal human range of hearing are called __ULTRASOUND__.

12. PITCH AND FREQUENCY
Sound waves with frequencies below the human range of hearing are called __INFRASOUND__.

13. CHANGING PITCH Changing Pitch
To speak air _VIBRATES__ your vocal cords.
Stretched vocal cords produce _HIGHER_ frequency.
Relaxed vocal cords produce __LOWER__ pitch
Brain Pop = Voice

14. THE DOPPLER EFFECT The Doppler Effect
The change in frequency of a wave as its source moves in relation to a observer is called the _DOPPLER EFFECT__.
The change in frequency is heard as a change in __PITCH__.
The Big Bang Theory Clip (1:15)
Doppler Effect Video (2:01)

15. THE DOPPLER EFFECT What Causes the Doppler Effect
When the source moves toward a listener, the _FREQUENCY__ of the wave is _HIGHER_ than it would be if the source were stationary.
The Big Bang Theory Clip (1:15)
Doppler Effect Video (2:01)