Place your palm about 1 foot in front of your mouth. Count from one to ten. As you count, slowly bring your palm closer to your mouth. Most likely, by the time you reach “five” you’ll feel the sound waves as they strike your hand. Now keep you palm about 6 inches from your mouth. Again, count from one to ten. Can you “feel” the difference in the sounds of each number?
Things Required:
Cardboard tube (from a finished roll of toilet paper)
Wax paper
Rubber band
Sequin or mirrored plastic chip
Glue
Pair of scissors
Torch
Directions:
Cut out a 4-inch-square wax paper. Stretch the paper over one end the cardboard tube. Pull it tight to form a flat surface. Slip a rubber band over the wax paper to keep it in place.
Use glue to secure a sequin to the centre of the wax paper. Hold the open end of the tube to your mouth. Use your other hand to aim the torch beam at the sequin. Stand near a wall so that you can locate the reflected spot of light. Talk loudly into the tube. Observe how you or voice affects the spot.
This Is What Happens:
As you spoke, you produced sound waves. These waves (which consist of pushed-together particles of air) moved outward from your mouth and travelled into the tube. At the far end of the tube, the waves struck the wax paper. This collision caused the stretched paper to vibrate. As the paper moved, the spot of light reflected by the sequin traced out the vibration pattern.
