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Ch. 18 - Waves & Sound. II. The Nature of Sound Speed of Sound Human hearing Doppler effect Seeing with sound. A. Speed of Sound. 344 m/s in air at 20°C Depends on : Type of medium travels better through liquids and solids can’t travel through a vacuum Temperature of medium

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Ch 18 waves sound
Ch. 18 - Waves & Sound

II. The Nature of Sound

  • Speed of Sound

  • Human hearing

  • Doppler effect

  • Seeing with sound


A speed of sound
A. Speed of Sound

  • 344 m/s in air at 20°C

  • Depends on:

    • Type of medium

      • travels better through liquids and solids

      • can’t travel through a vacuum

    • Temperature of medium

      • travels faster at higher temps


B human hearing
B. Human Hearing

sound wave

vibrates ear drum

amplified by bones

converted to nerve impulses in cochlea


B human hearing1
B. Human Hearing

  • Pitch

    • highness or lowness of a sound

    • depends on frequency of sound wave

    • human range: 20 - 20,000 Hz

ultrasonic waves

subsonic waves


B human hearing2
B. Human Hearing

  • Intensity

    • volume of sound

    • depends on energy (amplitude) of sound wave

    • measured in decibels (dB)


B human hearing3
B. Human Hearing

DECIBEL SCALE

120

110

100

80

70

40

18

10

0


C doppler effect
C. Doppler Effect

  • Doppler Effect

    • change in wave frequency caused by a moving wave source

  • moving toward you - pitch sounds higher

  • moving away from you - pitch sounds lower


C doppler effect1

lower frequency

higher frequency

C. Doppler Effect

Stationary source

Moving source

Supersonic source

waves combine to produce a shock wave called a sonic boom

same frequency in all directions


D seeing with sound

Medical Imaging

SONAR

“Sound Navigation Ranging”

D. Seeing with Sound

  • Ultrasonic waves - above 20,000 Hz