Sound is a wave

1. Sound is a wave S8P4 a: Identify the characteristics of electromagnetic and mechanical waves. S8P4 d: Describe how the behavior of waves is affected by medium (such as air, water, solids)

2. Vocabulary • Sound • Vibration • Vacuum • Echolocation • Sonar

3. Sound is a type of mechanical wave • Sound is a wave that is produced by a vibrating object and travels through matter • A vibration is a rapid, back-and-forth motion • The medium vibrates back-and-forth in the same direction as the disturbance, so sound waves are longitudinal waves.

4. Sound in our body • Sound-making instrument in your body is the vocal cords • Vocal cords relax when you breathe • They draw close together when you are about to speak so they can vibrate

6. How sound waves are detected • Ear collects sound waves • OuterEar—collects the sound waves, reflects to the ear canal, hits the eardrum at the end of the ear canal and causes it to vibrate • MiddleEar—vibrations travel through three bones (hammer, anvil, and stirrup) to the inner ear • InnerEar—Cochlea, which contains tiny hairs that bend due to the vibrations, triggers cells to send electrical signals to your brain. Only when your brain receives and processes these signals do you actually hear a sound.

7. Animation of ear • file:///D:/Animation%20List.html#

8. Drum: • Skin vibrates pushing particles in the air so they become compressed and moving out • When the drum pushes the opposite direction, the particles do not compress • longitudinal wave

9. Vacuum • A vacuum is empty space, has no (or very few) particles • Robert Boyle proved that sound does not travel through a vacuum • Bell inside a sealed jar and pumped all the air out, as he pumped the air out, the sound got quieter until it finally quit

10. Important Info on Sound • Is a mechanical wave • Only moves through a medium made of matter • Cannot travel through a vacuum—therefore, it cannot move through space!

11. The speed of sound • Sound travels slower than light • Two factors that affect the speed: • Material of medium • Temperature Materials: • Sound travels faster through liquids than gases, because of the amount of particles • Sound can travel through elastic solids very rapidly (steel)

12. The speed of sound Temperature: • Sound travels faster at higher temperatures than at lower temperatures • In hotter temperature the particles move faster making it easier to transfer sound waves • Sound waves will travel slower when someone yells in a snow storm than when someone talks softly on a hot summer day

13. Sound has many uses S8P4 e Relate the properties of sound to everyday experiences.

14. Ultrasound Waves • Humans and Animals use ultrasound waves to detect objects • Bats use the echoes to find food • People use it to detect objects underwater and/or to produce images of the inside of the body • Sound waves are used for much more than just communication!!

15. Echolocation • Echolocation is the sending out of ultrasound waves and interpreting the returning sound echoes • Animals use echolocation to find food • Bats • Dolphins • Toothed Whales • Porpoises

16. Bats use sound to locate objects.

17. Sonar • People use the principle of echolocation to locate objects underwater which uses the echoes to produce an image on a screen • A sonar is an instruments that uses echolocation to locate objects (sonar stands for “sound navigation and ranging”) • Used to locate enemies (submarines) • Find lost ships • Find schools of fish • Map the sea floor

18. Medical Uses • Can be used at high intensities because it cannot be heard by humans, therefore will not damage our hearing • Used to… • Break up kidney stones • Clean medical equipment • Examine internal organs like the heart, pancreas, bladder, ovaries, and brain • Examine blood flow

19. Medical Uses • Most common is the check on the health of a fetus during pregnancy • Helps determine gender of the baby • How many fetus there are • If there are any medical, or genetic, issues • The reflected ultrasound waves are used to create a picture called a sonogram

20. Ultrasound pictures “Sonograms”

21. Sound waves produce music • Music is sound with clear pitches or rhythms • Noise is random sound and has no intended pattern • All of the pitches, together with the resonance of the instrument, produce its characteristic sound

22. Musical Instruments There are three main types of instruments • Stringed • Wind • Percussion • Will discuss these later!!

23. Sound can be recorded or reproduced • Back in the day…there was no way to record or reproduce our voices. • In the late 1800’s, two inventions changed the world • 1876-the telephone was invented • 1877-phonograph was invented which was a sound recording machine

24. The telephone • Made long-distance communication possible • Telephones do two things • Translate the sound into a signal • Reproduce the sound that arrives as a signal

25. How the phone works

26. Recorded sound • This is a way to preserve sound because sound do not stick around, it is in real-time only • A recorder has a needle that takes the vibrations and cuts into a piece of foil. The grooves contain the information needed to reproduce the sound. • To play back, another needle is used to track along the foil • Now recorders change the sound waves into electrical signals as magnetic information instead of making holes