1. SOUND

2. Properties of Sound
The speed of sound depends on the medium it travels through.
Warmer medium  faster speed
Cooler medium  slower speed
Particles in cool materials move slower than particles in warm materials.

3. Properties of Sound
The pitch of a sound is determined by the frequency of a sound wave.
Pitch: how low or high a sound is perceived to be
High frequency = high pitch
Low frequency = low pitch

4. Properties of Sound Why does a drum get louder the harder you hit it?
This happens because more ENERGY is transferred to the drum the harder you hit it. The drum therefore transfers more energy to the AIR, which causes air particles to vibrate FARTHER from their rest positions.

5. Properties of Sound
The loudness of a sound is related to its amplitude.
Loudness: how loud or soft a sound is perceived to be
Larger amplitude = louder sound
Smaller amplitude = softer sound

6. Properties of Sound
Loudness is measured in DECIBELS.

7. Properties of Sound
An OSCILLOSCOPE converts the electric current produced by a microphone into a GRAPH, which allow us to see the difference in both FREQUENCY and AMPLITUDE of sound waves.

8. Properties of Sound Tuning forks video:

9. Properties of Sound The Doppler Effect:

10. Properties of Sound The Doppler Effect:
Apparent change in the frequency of a wave caused by the relative motion between the source of the wave and the observer.

11. Properties of Sound The Doppler Effect:

12. Read pp. 552-555 and fill in questions 8-12 on your notes.

13. How do instruments make sound?
How do instruments make sound?

14. Sound Quality
Sound Quality: The result of several pitches blending together through interference.

15. Sound Quality
String instruments produce sound when their strings vibrate after being plucked or bowed.
Thicker strings have a lower pitch.
Shorter strings vibrate at a higher frequency.

16. Sound Quality
Wind instruments produce sound when a vibration is created at one end of its air column, such as the lips of a trumpet player or reed of a clarinet.
A longer air column has a lower pitch.
The length of the air column can be changed by opening or closing the finger holes or pushing the valves.

17. Sound Quality Percussion instruments produce sound when struck.
The larger the instrument, the lower the pitch.

18. Sound Quality
Noise is any undesired or nonmusical sound that includes a random mix of pitches.