Sound
What Is Sound?
Sound is a vibration that travels through a material.
Sound is a form of kinetic energy.
Sound needs something (like air, water, or solid) to travel through. Thatâs why:
Sound waves are longitudinal waves â they move back and forth.
Sound cannot travel through a vacuum (because there are no particles).
â Sound travels faster in solids, slower in liquids, and slowest in gases.
â Sound travels fastest in solids because the particles are packed closely together.
đ” How Sound Travels
A vibrating object (like a guitar string) makes longitudinal waves.
These waves move through the air as compressions (where particles are squashed together) and rarefactions (where particles are spread out).
The part where particles are close together is called a compression.
The part where particles are spread out is called a rarefaction.
đ Measuring Sound
Term | What It Means |
Pitch | How high or low a sound is (depends on frequency). |
Volume / Intensity | How loud a sound is (measured in decibels, dB). |
Frequency | Number of waves per second, measured in hertz (Hz). |
Wavelength | The distance between two compressions or rarefactions. |
A higher frequency = higher pitch
Lower frequency = lower pitch.
đ« Sound and Vacuums
Sound cannot travel through a vacuum because there are no particles to pass on the vibrations.Thatâs why space is completely silent â even if a spaceship exploded, no one would hear it!
đĄïž Temperature, Altitude & Medium
The speed of sound in air increases with temperature.
Sound travels faster in warmer air.
At high altitudes, air is thinner, so sound travels slower.
Sound cannot travel through a vacuum, but it travels:
Fastest in solids (like metal),
Slower in liquids (like water),
Slowest in gases (like air).
đ How We Hear
Outer ear (pinna):Â Collects sound waves.
Middle ear (ossicles):Â Amplifies sound vibrations.
Inner ear (cochlea): Converts sound waves into electrical signals for the brain.
The eardrum converts sound waves into mechanical vibrations.
The brain interprets these as sound.
đ§ Extra Cool Sound Concepts
Sonic boom: Happens when something moves faster than sound (breaks the sound barrier).
Refraction: When sound waves change direction as they pass through different materials (like from air to water).
Reflection:Â Sound waves bounce off a surface.
A reflected sound wave is called an echo.
Materials like foam or curtains absorb sound.
Materials like steel conduct sound very well.
đ Fun Sound Facts
Speed of sound in air (room temp): about 343 m/s.
Human hearing range:Â ~20 Hz to 20,000 Hz.
Bats can hear some of the highest frequency sounds on Earth.
Sound waves can be reflected by walls or buildings.
Higher frequency = shorter wavelength.
Top Tips:
đ§ Use ear protection if sounds go above 85 dB â loud concerts or machinery can harm your hearing!
â Sound canât travel in space â thereâs no medium there.
đ§ Sound moves faster in steel than in air â solids are super speedy!
đ Keep ears healthy â all three parts (outer, middle, inner) play a big role.
đ§Ș Remember: Warm air = faster sound, Cold air = slower sound.