Groan, Squawk, Gong, and Whir!
What you need (1 set made ahead):
- Bullroarer (directions below)
Introduction:
Sound is produced by compression waves (waves that travel like an accordion). Those
waves strike your eardrum, and that membrane starts to vibrate. Those vibrations cause
an inner membrane to vibrate in a chamber filled with liquid, your inner ear. Those
vibrations are translated into the liquid. Tiny “hairs” in that inner chamber move from
the vibrations translated in the liquid, and your brain interprets that as sound. You can
use two of these experiments as demonstrations or to get attention from your audience.
The other two are quick activities for your participants to make and take.
Before the demonstration:
To make the Bullroarer, tie the string (about 3 feet long) through the hole of the ruler.
Stretch the rubber band lengthwise over the ruler. To operate, twirl in front of you or
over your head (like a lasso). If it isn’t very loud, twirl in the other direction. Change
speed. Optionally, you can make different sizes, including one as small as a plastic
spoon. Tie the string by the bowl of the spoon. Stretch a rubber band lengthwise over
the spoon. Twirl in front of you or over your head. Is the sound the same? Higher or
lower? Louder or softer?
To make the Quacking Duck, carefully punch a hole in the cup with a nail. Thread a
string (about 2 feet long) through the cup. Tie one end of the string to a large paperclip.
This needs to be on the outside of the bottom of the cup. The string should be hanging
out of the cup. On the other end, moisten and tie a sponge (about 1”x2” piece works
perfectly). With a moist sponge, pinch the string inside the bell of the cup and pull down
the length of the string. As the string becomes wetter, the sound gets louder.
Directions:
inside of the balloon.
Explanation:
All sound is caused by vibrations. There are all kinds of different sounds because
different materials vibrate differently.
For the Bullroarer, the air passes through the holes at a faster speed than the air that is
going around the ruler or plastic spoon. This causes the whirring, rushing air sound.
The cup on the Quacking Duck amplifies the sound, which is caused by the vibrating
string.
The beautiful chime sound you hear from clanging the nail while listening in the cup is
because the sound is traveling through solid (the string) rather than in the air. When you
clank the nail without holding the cup to your ear, the dull clank is only traveling through
the air. The difference in sound shows how much of the sound is lost in the air. Solids
and liquids are much better at carrying sound waves.
A hex nut has 6 sides, and these flat edges causing the hex nut to bounce inside the
balloon. The whirring sound is made by the sides of the hex nut vibrating against the
inside wall of the balloon.
What you need (1 set made ahead):
- Bullroarer (directions below)
- Thin ruler with hole in one end
- String
- Rubber bands
- Plastic spoons
- Heavy duty plastic cup
- Nail
- String
- Sponge
- Water
- Heavy duty plastic cup
- String about 18” long
- Large paperclip
- Large nail
- Large balloon
- Hex nut
Introduction:
Sound is produced by compression waves (waves that travel like an accordion). Those
waves strike your eardrum, and that membrane starts to vibrate. Those vibrations cause
an inner membrane to vibrate in a chamber filled with liquid, your inner ear. Those
vibrations are translated into the liquid. Tiny “hairs” in that inner chamber move from
the vibrations translated in the liquid, and your brain interprets that as sound. You can
use two of these experiments as demonstrations or to get attention from your audience.
The other two are quick activities for your participants to make and take.
Before the demonstration:
To make the Bullroarer, tie the string (about 3 feet long) through the hole of the ruler.
Stretch the rubber band lengthwise over the ruler. To operate, twirl in front of you or
over your head (like a lasso). If it isn’t very loud, twirl in the other direction. Change
speed. Optionally, you can make different sizes, including one as small as a plastic
spoon. Tie the string by the bowl of the spoon. Stretch a rubber band lengthwise over
the spoon. Twirl in front of you or over your head. Is the sound the same? Higher or
lower? Louder or softer?
To make the Quacking Duck, carefully punch a hole in the cup with a nail. Thread a
string (about 2 feet long) through the cup. Tie one end of the string to a large paperclip.
This needs to be on the outside of the bottom of the cup. The string should be hanging
out of the cup. On the other end, moisten and tie a sponge (about 1”x2” piece works
perfectly). With a moist sponge, pinch the string inside the bell of the cup and pull down
the length of the string. As the string becomes wetter, the sound gets louder.
Directions:
- Twirl the Bullroarer for attention.
- Quack the Quacking Duck.
- Ask, what is common about these two sounds? Wait for replies. (Both are made from
- Beautiful Chimes – distribute plastic cups, string, paperclips and nails.
- Direct participants to up the cup with the bottom up. With the nail, carefully put a hole in
- Thread the string through the hole. On the outside of the bottom of the cup, tie the nail.
- On the inside of the bottom of the cup, tie the paperclip.
- Pull the string on the nail side, until all of the string is coming out of the bottom on the
- Direct participants to place their ear over the open end of the cup, and gently swing the
- Wow!
- Twirl the Bullroarer for attention.
- Quack the Quacking Duck.
- Ask, what is common about these two sounds? Wait for replies. (Both are made from
- Whirring Balloon – distribute balloon and hex nut.
- Instruct the participants to squeeze the hex nut through the neck of the balloon.
- Blow up the balloon about half full (WARNING – ONLY HALF FULL).
- Tie off the neck of the balloon.
- Holding the balloon in one hand at the neck, palm down and fingers and thumb extending
inside of the balloon.
- WOW!
Explanation:
All sound is caused by vibrations. There are all kinds of different sounds because
different materials vibrate differently.
For the Bullroarer, the air passes through the holes at a faster speed than the air that is
going around the ruler or plastic spoon. This causes the whirring, rushing air sound.
The cup on the Quacking Duck amplifies the sound, which is caused by the vibrating
string.
The beautiful chime sound you hear from clanging the nail while listening in the cup is
because the sound is traveling through solid (the string) rather than in the air. When you
clank the nail without holding the cup to your ear, the dull clank is only traveling through
the air. The difference in sound shows how much of the sound is lost in the air. Solids
and liquids are much better at carrying sound waves.
A hex nut has 6 sides, and these flat edges causing the hex nut to bounce inside the
balloon. The whirring sound is made by the sides of the hex nut vibrating against the
inside wall of the balloon.