Sound travels because the vibrations are passed
from molecule to molecule, therefore sound
requires a medium to travel through.
Examples: Solid, Liquid, Gas
The Speed of Sound
The Speed of Sound in air is about 340m/s.
This can change slightly if the temperature or air pressure changes.
The Speed of Sound in water is slower than in air.
Sound Waves travel fastest through
Solids and slowest through Gases.
(The Particles are closer together in a
solid which helps the vibrations travel
faster than a gas, as gas molecules are
Reflected Sound (Echo)
When Sound meets are hard,
flat surface, the sound wave is
reflected back from the
surface.This is what we call an
Echo: Is a Reflected Sound
The Human Ear and Loud Sounds
The scientific name for the
loudness of a sound is the Sound
Intensity Level. Here we call this
Sound Level. Sound Level is
measured in Decibels.
120 Decibles is the
loudest sound level you
should listen to.
120 Decibels will case pain in your
ear and most likely will result in
permanent ear damage.
Any sound above 70 Decibels can cause
harm to your ear, it is for this reason that
hearing protection is recommended for
Noise and Effects
Noise: A noise is any unwanted
sound.What one person might
consider noise another person might
Noise can cause hearing problems.
Three effects of Noise:
Three ways to reduce the effects of Noise: