Sound.

Sound.

1. Sound waves: sounds travel through the air, Sound waves are made by vibrations

   • Sound travels: sound waves travel through solids and liquids, The particles in solids and liquids are much closer
   • Musical instruments: use vibrations make sound changes the speed play notes of different pitch.
     • Parts of a guitar: body, frets, fingerboard, machine head.
       • The decibel scale: The loudness of a sound is measured in decibels (dB)

2. Sound reflection and absorption: sound energy is reflected from hard surfaces such as walls and rocks.

3. Echolocation: the sounds bounce off the walls of caves and the bats use the echoes to find their way about, bats' p

4. Loud sounds can damage your hearing. Short exposure to sound levels above 130 dB or long-term exposure to above 100 dB can use permanent damage.

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