WHAT IS SOUND ENERGY?
WHAT IS SOUND?
• Sound- a wave of vibrations that
spreads from its source.
• Vibration is the back and forth motion of an
object.
• As sound waves travel through a
material, the molecules make it up
vibrate in a kind of pattern.
• They get closer together then farther apart.
WHAT DETERMINES THE LOUDNESS OF A SOUND?
• Vibration- Back and forth movements that can travel through
air, liquids, and solids.
• Pitch- an element of sound determined by the speed at which
sound waves travel.
•
•
The higher the frequency is, the higher the pitch of the sound.
The lower the frequency is, the lower the pitch of the sound.
• Volume- The loudness of a sound
•
•
Sound gets louder when the source of the sound is vibrating more.
The loudness of a sound is measure in decibels.
HOW DOES SOUND BEHAVE?
• Sound can travel through solids, liquids, and
gases.
• It travels fastest through solids because the
molecules are closer in a solid.
• Sound cannot travel through a vacuum, which
is an empty space that contains no particles.
• Without vibrating particles, sound cannot exist.
• So, there is no sound in outer space.
• The speed that sound travels is different
based on the material.
WHAT HAPPENS WHEN SOUND HITS AN OBJECT?
•
When sound waves reach the border of different materials
three things can happen: Transmission, Reflection, or
Absorption.
•
Transmission of Sound- sound waves that pass through
materials are transmitted. This means that sound can travel
through objects.
•
Reflection of Sound- Sound that bounces off of on object is
reflected, and this creates an echo.
•
Absorption of Sound- When sound hits a wall, some
bounces back, some doesn’t. sound waves that get “lost” or
absorbed have been turned into heat energy. Because the
Sound has been absorbed, we hear a quieter sound.
EXAMPLES OF WHAT HAPPENS WHEN A SOUND
HITS AN OBJECT
• If a cell phone is ringing and it is in your pocket,
you can still hear it ringing through the fabric of
your pocket. (Transmission)
• Echo- occurs when sound waves reflect (bounce)
off of something.
• With sound proofing, the sound bounces around
and inside the soundproofing many times.
• The material absorbs nearly all of the sound waves that
•
strike it.
This causes the sound to become muffled.
SOUND TRANSFERS ENERGY
• For a sound to be heard, energy must first cause an
object to vibrate.
• As sound waves move, the energy is transferred
through the air.
• Some of the energy reaches your ear, and your eardrum
absorbs some of the energy and it begins to vibrate, which
allows you to hear the sound.
SOUND IN A BELL JAR
https://www.youtube.com/watch?v=Fa0c9ONZMck
YOUR VOICE
• Your vocal chords vibrate when you talk.
• The vibrations are caused by air rushing past them.
• The vibrations travel outward through the air as sound
waves.
• The sound waves travel in all directions
• Even people behind you can hear what you are saying.