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What is Sound Sound wave: a longitudinal wave that is caused by vibrations and that travels through a medium. Particles vibrate back and forth along the path sound travels. Sound waves travel in ALL directions away from the source.

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Properties of Sound The speed of sound travels at different rates according to the medium.

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Properties of Sounds Pitch: a measure of how high or low a sound is perceived to be, depending on the frequency of the sound wave High frequency= high pitch Low frequency=low pitch High amplitude- louder sound Short amplitude= soft sound

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Doppler Effect Doppler effect= an observed change in the frequency of a wave when the source or observer is moving. As the sound approaches; pitch and frequency increase As the sound passes; pitch and frequency decrease

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Car Sounds Listen to the following sounds and try to figure out what these sounds have in common.

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Sound When a drummer hits a drum harder to produce a louder sound, which part of the sound wave changes and how? a. The length of 1 increases. b. The height of 2 increases. c. The length of 1 decreases. d. The height of 2 decreases. 2 1

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Sound Children were playing in a lake. Why would they be able to hear a motorboat coming when they were underwater before they could hear it above the water? a. Sound waves travel faster in air than in water. b. Sound waves travel faster in water than in air. c. Sound waves are stronger when they travel through water. d. Sound waves are stronger when they travel through the air.