1. SOUND
Science

2. What Makes Sound?
vibration – a back and forth movement. To produce sound an object must be vibrating.
energy transfer
Speech is produced
by vibration of vocal
chords.

3. How Does Sound Travel?
Sound is a vibration that travels through matter.
As vibration occurs, molecules in the air squeeze together and then spread apart.
compression – the part of sound wave where molecules are crowded together
rarefaction – the part of the sound wave where molecules are spread apart

4. sound wave – a vibration that spread away from a vibrating object.

5. How Do You Hear Sound?
Outer Ear – Acts like a funnel to direct sound waves to the eardrum
Middle Ear – The vibrating continues on to the hammer, anvil, and stirrup
Inner Ear – The vibrating continues to a fluid filled tube
Nerve to Brain – Hair cell vibrations from tube pass on to the auditory nerve and onto the brain.

6. Your Ear!

7. Can Sound Travel Through Anything?
Sound can travel through all forms of matter (including solids and liquids).

8. How Can You Change a Sound?
pitch – how high or low a sound is
Higher pitched sounds will have a greater frequency of sound waves.
frequency – the number of times an object vibrates per second
hertz – a unit for measuring frequency

9. What Makes Sound Loud? Energy of Sound Waves
Decibels – a unit for measuring loudness
Loudness is the human
perception of the
energy waves carry.

10. How Is Sound Recorded? Step 1: Change Sound Into Electric Current
Step 2: Make the Current Stronger
Step 3: Change Current to Magnetic Pattern
When you speak molecules are colliding!

11. Do Sounds Bounce?
reflection – the bouncing of a sound wave off a surface
Example – the crack of the baseball bat
absorption – the disappearance of a sound wave into a surface
Example – the sound of a baseball hitting the glove

12. What Is An Echo?
echo – a reflected sound wave

13. What Can Echoes Do? Sonar navigation – maps out the ocean floor
Echolocation – the finding of an object by using reflected sound
Example – Whales and dolphins use this to find objects
Example – Bats use this to find their prey

14. How Do Moving Sounds Change?
Doppler effect – the change in frequency (and pitch) as a source of sound moves toward or away from you. As you move away from a building the siren will sound lower.

15. What’s the Difference?
Quality – the difference you hear in two sounds of the same loudness and pitch
Fundamental frequency – the lowest frequency at which an object vibrates
Overtone – the number and intensity overtones produces by each instrument give the instrument their distinctive sound.
Resonance can be used to amplify sound.
Music- a combination of sounds with distinct pitches and patterns.