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This week's experiment came from a student at one of my shows. While
waiting for my show, he was having fun with this fun method of making sounds,
and I just had to try it too. Soon, half of the kids in the audience were having fun with it, so I thought you might enjoy it too.
Materials:
You will need:
Your hand and your mouth
Plan:
The first thing to do is to shape your mouth. Pretend that you are going to
say "Ooooo". Then hold your hand out flat, with your palm up. Quickly,
but gently, pat your hand against your mouth. Do this gently. You don't want
it to hurt. Listen carefully to the sound that it makes. Done properly,
you should hear a popping sound, which was made famous by a comedy actor named
Fritz Feld. He often played the head waiter in the old comedy movies.
Once you can make the sound, try changing the shape of your mouth. Open
your lips a bit. Close them a bit. Open your jaw a bit wider. With each
change, try making the popping sound again. You should hear the sound change
each time. Why? When you pat your hand against your mouth, you are compressing the air a bit.
That causes the air in your mouth to vibrate, which produces a sound. You
can get a similar result by patting your hand on the mouth of a tall, narrow
glass or vase. The sound waves in your mouth bounce around in there. The size and shape of
the opening will cause some of the sound waves to be canceled out, while
others add together to make a louder sound. That will cause the sound to
produce
a specific tone. When the shape of the opening in your mouth changes, the
waves that are louder will change, so the tone that you hear will change. This is very similar to the way that many wind instruments work. Opening
and closing holes or moving a slide will change the size and shape of the
opening inside the instrument, which once again changes the tone that you hear.
I
guess if you practiced, you could learn to play a tune with mouth pops. It
sure would be fun to try.
From Robert Krampf's Science Education Company
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