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Sound (How sound travels (thing or person making noise creates vibrations…
Sound
How sound travels
thing or person making noise creates vibrations 1
air molecules around the noise creating machine vibrates 2
vibration of air molecules continues across space 3
air in ear canal vibrate to 4
energy falling on our ears is perceived 5
Sound is a form of energy, sound made from vibrations
sound is produced when objects vibrate
diaphragm of speaker vibrates to make sound
guitar strings vibrate to make sound
ruler on the end of a table and flick it vibrates
Speed of sound and speed of light
value of speed of sound 340ms
value of speed of light 300 000 000 ms
comparisions
you see lightning before you hear thunder
you see a firework explode before you hear sound
ear protection
120 decibels or higher will hurt ears and result in permanent ear damage
70 decibels can cause damage
hearing protection required by law in working places with loud noises
Human Ear and loud noises
loudness of sound = sound intensity level
sound intensity level measured in decibels,
use page 352 figure 40.10
Reflection of sound
sound bounces off hard smooth surface like a wall or cliff face