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SPS9 Students will investigate the properties o f waves.

SPS9 Students will investigate the properties o f waves. Ch. 18 - Waves & Sound. II. The Nature of Sound Speed of Sound Human hearing Doppler effect Seeing with sound. Sound. A. Speed of Sound. 344 m/s in air at 20°C Depends on : Type of medium

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SPS9 Students will investigate the properties o f waves.

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  1. SPS9 Students will investigate the properties of waves.

  2. Ch. 18 - Waves & Sound II. The Nature of Sound • Speed of Sound • Human hearing • Doppler effect • Seeing with sound

  3. Sound

  4. 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

  5. B. Human Hearing sound wave vibrates ear drum amplified by bones converted to nerve impulses in cochlea

  6. Page 325 blue

  7. B. Human Hearing • Intensity • volume of sound • depends on energy (amplitude) of sound wave • measured in decibels (dB)

  8. 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

  9. Medical Imaging SONAR “Sound Navigation Ranging” D. Seeing with Sound • Ultrasonic waves - above 20,000 Hz

  10. Wave speed = frequency x wavelength V = f x λ The speed of a wave depends on its Medium.

  11. Pitch How high or low a sound seems to be. Is related to the frequency of sound waves.

  12. When a musician plays a note of a certain pitch, the musical instrument vibrates or RESONATES and produces a complex pattern of sound waves made up of many different frequencies. Musical instruments often make very quiet sounds, but some are designed to AMPLIFY the sounds they make so we can hear them more easily.

  13. The most noticeable sound wave is called the fundamental, but there are other waves with higher frequencies, called harmonics.

  14. C. Harmonics • Fundamental • the lowest natural frequency of an object • Overtones • multiples of the fundamental frequency

  15. Notes from a flute sound more pure than those from a saxophone because they contain fewer harmonics.

  16. Anechoic chamber - designed to eliminate reverberation. E. Acoustics • Acoustics • the study of sound • Reverberation • echo effect produced by the reflection of sound

  17. D. Interference • Beats • variations in sound intensity produced by 2 slightly different frequencies • both constructive and destructive interference occur

  18. Concert Halls and Interference The curved shapes in modern concert halls are designed to help distribute the sound evenly to every seat in the auditorium.

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