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Transcript investigations

And how is it made?
CRASH! BANG! Did you hear that sound?
It was made by air vibrating.
Listen to the following sounds
Write down what you think is making the sound.
child laughing
What's going on?
Our brain can determine quickly all kinds of different
Notice how just very small differences in the sound we
heard was just enough for you to figure out what each
one was.
You might be wondering, how is sound produced?
Cassie has the answer! Watch this video to find out!
Herring Hellos
by Meg Dorman, art by Charles Stubbs
We've all heard birds chirp and squirrels chatter. Apparently, small fish
called herring also talk to their friends, though not with their mouths.
Instead, a herring with something to say swims to the surface for a gulp
of air, then blows the air out a hole in its behind. To the human ear, the
burst of bubbles this produces sounds like a high-pitched squeak. But
to a herring, it's hello. Scientists with a sense of humor have named this
herring-speak Fast Repetitive Tick, or FRT, for short.
When scientists first heard the noise, they were puzzled about just
why herring were breaking wind. Then scientists noticed that the
herring usually made the noise in the dark and that they increased
their FRTs when more herring were around. Conclusion: The FRTs
were a way for herring, which swim in groups, to stay together in the
dark. Because the high-pitched FRTs are impossible for most other
fish to hear, the herring can say “Hey, where are you?” without
alerting predators.
We, as humans, have created many more sounds.
Some of these sounds are what we would call
Many hundreds of years ago, people found that certain things, such as a metal
wire, when plucked, produced a pleasant sound.
Over the years the people created many musical instruments from that simple
Many other musical instruments came directly from what people saw and
heard around them.
People observed nature and learned to imitate the sound they heard.
See if you can think of some musical instruments that sound like the sounds of
A musical sound is produced by air vibrating a certain number of times per
second. These vibrations are called waves.
The number of times that a sound wave vibrates in a second is called its
High notes have a higher frequency than lower notes and this changes their
Different types of sound waves have different shapes. Look at these images
to see what sound waves "look" like.
Tape some paper tightly over one end of a cardboard tube.
Sing into the tube, gently touching the paper.
Can you feel the vibrations?
Try making your voice higher or lower, and notice the different types
of vibrations.
The sound of our voice seems to be made louder by
humming into the kazoo because the kazoo
resonates or vibrates with the sound of your voice.
As your voice travels down the cardboard tube and
reaches the wax paper, the wax paper vibrates and
all those harmonics get amplified (made louder).
Some people call this music, some call this noise.
Wrap a rubber band around your fingers.
Pluck it a few times.
Can you see and feel the vibrations?
The harder you pluck the rubber band, the more
it will vibrate, creating a louder sound.
(It will be a higher pitch.)
If you stretch the rubber band, making it longer
and thinner, what do you hear?
Tap an empty metal tin with a spoon.
Feel it vibrate as it makes a sound.
Fill an empty glass bottle with water almost to
the top.
Take a pencil, and gently tap it.
Fill other bottles with different amounts of
water in them.
Do the bottles sound differently?
The more water in the bottle, the lower the
pitch, because the vibrations are slower.
Tuning Forks and Vibrations
Tuning forks always make the same clear sound.
Hold the rounded handle.
See that the two "tines" make a narrow letter "U".
Find the rubber strike plate.
(The tines must only be struck on the strike plate,
because they may become bent or broken if they
are struck against a hard object.)
Keep your eyes on the tines as you tap one of the
tines on the striker.
Strike the fork – the movement is a
Touch your cheeks with the vibrating fork.
What do you feel?
If you put a silent fork against your face, does it tingle?
Why not?
Can we see vibrations travel through the air?
Let the end of the handle touch the table, while their hand moves
up a bit closer to the "u" to keep the fork upright.
Has the sound changed?
Do this again and put your ear down on the table.
What do you hear?
What can you feel?
Gently place the vibrating tuning fork in a beaker of water.
Observe what happens to the water and to the pitch and duration of
Try placing a vibrating fork on other surfaces:
a chair
a file cabinet
the floor
a book
the teacher's desk
a recess ball
a lunch box
Can you find patterns in what made the fork's sound louder?
Can you find patterns in what made the fork's sound softer?
Can the vibrations move more easily through air or a solid?
Choose a new site to place your vibrating fork.
Predict whether the sound will be louder or softer.
Make a line by the science table.
The person at the front of the line will tap a tuning fork and hold it in the air.
The other children will raise their hands if the sound can be heard from their
place in line.
Now place your ear on the table.
The leader will tap the tuning fork on the table.
The other children will raise their hands if the sound can be heard from their
place in line.
Could more students hear the sound when it was travelling along the pipe?
Native Americans placed their ears on the ground to hear horses
approaching; snakes receive all their information through these vibrations in
the ground - since they don't have ears.