SUBJECT AREAS: Physics and Physiology

CONCEPTS: Sound, hearing, vocalization.

MATERIALS:

1. Empty coffee can

2. Disposable latex gloves

3. Pieces of a broken mirror (a compact mirror works really well)

4. Glue

5. Tape and/or rubber bands

6. Flashlight or laser beam

PROCEDURE:

1. Cut both sides of the coffee can off with a can opener.

2. Stretch the latex over one side of the can and keep it in place with the rubber bands and the tape.

3. Break a mirror and glue one of the pieces on the outside of the latex. Usually a piece of about one square inch works well.

4. In a dark room, have one person shine the flashlight on the mirror piece. Have the other person hold the can and yell into open end.

5. Watch the light patterns that form on the wall. Experiment with different voices. Try different volumes, pitches, words and people.

QUESTIONS:

1. What causes the different patterns on the wall?

2. Why does the mirror on the latex vibrate?

3. What happens when you change the pitch, volume, or tone of the voice being used?

4. How is this similar to your ear drum? How about your vocal cords?

RATIONALE:

The sound waves from the speaker's voice causes the latex to vibrate like an ear drum or a vocal cord. These vibrations change according to the pitch (how high or low the voice is), the volume, and the tone of the voice. The different kinds of vibrations show different light patterns on the wall. If you make enough of these, you could have your own musical "laser light show" in your classroom.

APPLICATION: Eardrums, vocal cords, percussion instruments.