Sound Waves
What is sound?
Goal:
Goal:
You can hear it in the forest, you can hear it in the town, and you can hear it inside--but what is sound? Click through the slides below to find out all about what sound is and how it moves.
What is sound?
Sound is energy you can hear, but NOT see. Sound travels through air, water, or other materials in waves. Sound waves are not like the waves you see on water or the waves you make by swinging a rope back and forth. Sound travels in compression waves.
What do sound waves look like?
Find out what sound waves look like by trying this
activity.
Take a walking spring toy, like the one shown in the
picture, and stretch it loosely across the surface of a
table. Have a friend hold the other end. Now, quickly
jerk your end straight toward your friend and back
again. You should see a compression wave travel the
length of the coil. This is what sound waves would look
like if you could see them!
How does sound travel?
You know you can hear sound, but did you know you could
feel sound too? The movement of sound is called a
vibration. A vibration is when
something moves very quickly. Different types of
vibrations make different sounds.
Look at the picture. When you pluck a guitar string, it
moves very fast. This vibration is what makes the sound.
What are loud and soft sounds?
A big vibration causes a loud sound, and a tiny vibration causes a soft sound. The closer you are to the source of the sound, the louder that sound will be.
What are high- and low-pitched sounds?
How fast the wave is vibrating will tell you the pitch
of the sound. Pitch is how high or how low a sound is. A
slow vibration has a low sound, like a bass drum or a
roll of thunder. A fast vibration has a high sound, like
a bird’s cheep or a whistle.
The bat in the picture makes very high-pitched sounds.
The vibrations are so fast that the human ear cannot
hear them.
Question
Will a sound be louder or softer when you are closer to its source?
The sound will be louder. When you are closer to the thing that is making the sound, it will be louder than if you are standing far away.