1. Chapters 20-21 Sound and Musical Sounds Ch20 Homework:
RQs: 3, 5, 7, 8, 20, 21, 24.
Ch21: Read pp

2. Sound Waves pressure/density waves compressions rarefactions
speed about ____________________ but changes with temp. & pressure

3. Properties of Sound About 4x faster in water
About 10x faster in solids
Reflection
Refraction
Diffraction
Interference

4. Sound Intensity and Loudness
intensity = power per unit area
“loudness” is the human perception of sound intensity
sound level dB (decibels) is ________________________________

5. Natural Frequencies: Waves on Strings
Nodes (N) are places with zero amplitude
Anti-nodes (A) are places with maximum amplitude

6. resonance frequency of disturbance = ____________ Example: swing
Examples: tuning forks, guitar strings

7. hearing “audible range”: ____________________
Affected by age, genetics, and exposure (music, workplace, etc)
Relation to size of ear:
dogs, cats (50Hz < f < 45,000 Hz)
bats up to 120,000 Hz
elephants as low as 5Hz

8. summary Sound is a longitudinal wave
Reflection, refraction, diffraction, and interference
Intensity of sound
hearing