As you learned, structures within a sperm whale's head affect the behavior of sound waves. Some materials reflect sound, while others absorb it. Still others, such as the liquid within the sperm whales, are good transmitters of these waves. In this activity, you'll observe firsthand how various materials reflect and absorb sound.
Kitchen counter timer (wind-up type)
Long cardboard tube (insert in wrapping paper roll)
Variety of materials such as wood, paper, acoustic tiles, fabrica, soft foam, filled plastic bag
CAUTION: Never place any object into the ear.
1. With your instructor, review safety techniques when placing objects near the outer ear.
2. Working in teams of two, identify a desktop or floor space that aligns with a wall.
3. Wind up the kitchen timer. Place it several inches from the wall.
4. Wrap your hand around one end of the cardboard tube with your thumb and index finger encircling the tube edge, forming a soft cushion.
5. Place this “cushioned” tube end next to your outer ear.
6. Position the free end of the tube so that it points to the wall as shown. Make sure that the end of the tube is several inches from the wall.
7. Listen to the clicks made by the kitchen timer.
8. Position a piece of wood against the wall at the point where the sound is reflected off the wall and into the cardboard tube. Listen to the clicking and describe any change in the sound.
9. Replace the wood with other materials. Record how each material affects the sound.