Sound is energy that travels in waves through substances. When an object vibrates, it makes the air around it vibrate, and those vibrations travel to your ears. No vibration = no sound!
π How Sound Travels
- Sound travels in waves
- Sound needs a medium β it can't travel through a vacuum (space)
- Sound travels fastest through solids, slower through liquids, slowest through gases
- Speed in air β 343 m/s
βΏβΏβΏβΏβΏβΏβΏβΏβΏβΏ β π
Compression waves moving through air
π Properties of Sound
πΌ
Pitch
How high or low a sound is
Depends on frequency (vibrations per second)
High frequency = high pitch (whistle)
Low frequency = low pitch (thunder)
π’
Volume (Loudness)
How loud or quiet a sound is
Depends on amplitude (size of vibration)
Big vibrations = loud sound
Measured in decibels (dB)
π How We Hear
- Sound waves enter the ear canal
- They make the eardrum vibrate
- Tiny bones amplify the vibrations
- The cochlea converts vibrations to electrical signals
- Signals travel to the brain β we "hear" the sound!
π Sound Levels
- π€« Whisper: ~30 dB
- π£οΈ Normal talking: ~60 dB
- π Traffic: ~80 dB
- πΈ Concert: ~110 dB
- βοΈ Jet engine: ~140 dB (painful!)
Warning: Sounds above 85 dB can damage hearing over time!
βοΈ Activities
Find examples of different sounds around you:
- High pitch: ___________
- Low pitch: ___________
- Loud: ___________
- Quiet: ___________
Why can't astronauts hear each other talk in space without radios?
π©βπ« Teacher Notes
- Science: Physical World β energy, waves