This Week's Experiment - #293 Comb Kazoo
I had a chance to talk with my good friend Mik Jacobs (The Fire Guy).
He is now set up in Florida, doing science theater development and fire
safety shows (http://www.MIKJACOBS.com/). We were swapping science ideas
and he asked if I had ever done an experiment with a comb kazoo. That led
to an interesting discussion and this week's experiment. To try this
classic experiment in sounds, you will need:
some waxed paper, tissue paper, or other thin paper
All right, I admit that I have never been very musical. About the only
musical instrument that I play well is the radio. Still, with this week's
experiment, even I can make music, or at least something close enough to
cause Lisa to ask me what that noise is.
Cut a piece of waxed paper that is as long as your comb and wide enough so
that if you fold it in half, it will cover the comb. Hold the comb with the
teeth pointing downwards. Fold the waxed paper in half and place it over
the comb. Hold the paper lightly against the comb. Place the paper and comb lightly against your lips and say "Oooooooooo".
You may have to try several times, but when you get it right you will know.
The waxed paper will vibrate, making a buzzing sound with a pitch similar to
the sound you are making. The vibration will also cause a tingling
sensation on your lip.
Once you get the hang of it, it is really very easy. The best part is that
you can now play any song that you can hum. You don't even have to know the
words. This is a version of a musical instrument called a kazoo.
OK, so we have a fun thing to play with, which also has the added benefit of
making lots of noise to annoy big brothers, etc. But where is the science?
Actually, this is a very nice way to explore the basics of sound. In
studying sound, we study vibration. Anything that is making a sound is
vibrating. Is your kazoo vibrating? Yes! That is what makes your lip
What causes the kazoo to vibrate? Place the back of your hand gently
against your lips and hum the same way you did for the kazoo. Again, you
feel vibrations. Where are those vibrations coming from? Put your fingers
lightly on your throat and hum again. Ah! The vibrations are coming from
your vocal cords in your throat. Air from your lungs moving across the
tight vocal cords causes them to vibrate. That causes the air in your
throat and mouth to vibrate. The vibrations are transferred from the
vibrating air to the paper of the kazoo.
The vibrating paper then causes the air around it to vibrate. Because the
paper is flexible and loose, it distorts the vibrations, giving the kazoo its
interesting sound. The vibrations spread through the air just as waves
spread across the surface of a pond. When the vibrations reach your ears,
they cause your ear drum to vibrate, just as the vibrating air from your
mouth caused the waxed paper to vibrate. Your ear drum passes the
vibrations along through a series of tiny bones (The hammer, anvil and
stirrup are the smallest bones in your body.) and then to your inner ear.
This is a snail-shell shaped structure filled with liquid. When the liquid
vibrates, it moves nerves which send a message to your brain which you
interpret as the sound. The vibrations are transferred from object to
object, vocal cords to air to paper to air to ear drum to the series of tiny
bones to inner ear.
And now for the answer to all of those out there that know how "hair
challenged" I am. I did not have a comb, since I usually don't have much
use for one. Lisa gave me one for the experiment, and of course I promised
that I would never part with it. (grin)
These experiments are from Robert Krampf - The Happy Scientist
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