The document discusses sound waves and their characteristics including pitch, intensity, and frequency. It explains that sound is produced by vibrating objects like tuning forks and transmitted through compression and rarefaction waves. Pitch can be manipulated through effects like the Shepard tone which uses superposition of waves to create the illusion of a constantly increasing pitch. Intensity decreases with the inverse square of distance from the sound source and is measured in decibels on a logarithmic scale. The human range of hearing is from 20-20,000 Hz and our ears detect sound through the eardrum, hammer, anvil, stirrup, cochlea and auditory nerve.

3. • Production
–Vibrating Objects
Sound Waves
• Tuning fork
–Compression
–Rarefaction
• What type of wave is sound?

5. • Characteristics
– Pitch
• Shepard tone (auditory illusion)
Sound Waves
Superposition of waves an octave
apart. Makes it sound like the pitch is
constantly increasing.
• Doppler Effect
– Human Hearing
– 20-20,000 Hz
• Infrasonic
• Ultrasonic  ‘Stealth tones’

6. Power
Intensity =
4π r 2
• Relationship between distance
Intensity
from source and intensity?
• Relative intensity (loudness)
– Decibels (dB)
• Logarithmic scale
• 10dB  20dB increase of 10X

7. Intensity (W/m2) Decibel level (dB) Examples
1.0x10-12 0 Threshold of hearing
1.0x10-11 10 Rustling leaves
1.0x10-10 20 Quiet whisper
1.0x10-9 30 Whisper
1.0x10-8 40 Mosquito buzzing
1.0x10-7 50 Normal conversation
1.0x10-6 60 Air conditioning at 6 m
1.0x10-5 70 Vacuum cleaner
1.0x10-4 80 Busy traffic, alarm clock
1.0x10-3 90 Lawn mower
1.0x10-2 100 Subway, power motor
1.0x10-1 110 Auto horn at 1m
1.0x100 120 Threshold of pain
1.0x101 130 Thunderclap, machine gun
1.0x103 150 Nearby jet engine

8. • Natural Frequency
– Resonance
• Tacoma Narrows Bridge
• Beats
Other Stuff
– Difference in the frequency
• Hearing
– Eardrum
– Hammer, anvil, stirrup
– Cochlea
– Auditory nerve

9. • Natural Frequency
– Resonance
• Tacoma Narrows Bridge
• Beats
Other Stuff
– Difference in the frequency
• Hearing
– Eardrum
– Hammer, anvil, stirrup
– Cochlea
– Auditory nerve