1. What is sound? Sound is a longitudinal wave which travels through the air through a series of compressions and rarefactions.

2. Sound Waves -Alternating areas of high & low pressure in the air -Sound waves move out in ALL directions from a vibrating object

3. Speed of Sound 343 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

4. Pitch A measure of how high or low a sound is Pitch depends on the frequency of a sound wave For example, Low pitch Low frequency Longer wavelength - High pitch - High frequency - Shorter wavelength

5. Pitch –highness or lowness of a sound –depends on frequency of sound wave –human range: 20 - 20,000 Hz ultrasonic waves infrasonic waves

6. Loudness –volume of sound –depends on energy (amplitude) of sound wave, the greater the amplitude the louder the sound –measured in decibels (dB)

7. Loudness in Decibels

8. What is the Doppler Effect? The Doppler Effect is the apparent change in frequency detected when the sound is moving relative to the hearer. http://video.google.com/videoplay?docid=- 888534110918986008&ei=APeQSaHKG4iGqwLQu8W2Cw&q=doppler+effect&hl=en

9. Sonar The detection of reflected sound waves The sonar detects the time it takes to send out a sound wave and get the reflected wave back. Since we know how fast sound can travel in water, the distance can be calculated.

10. Echolocation Used by dolphins and bats to get food Sends out sound waves greater than 100,000 Hertz Humans cannot hear

11. Ultrasound Used by doctors to look inside the human body. 4 million Hertz Toothbrushes, cameras