Sound Viewer

Learning Objectives

In this activity, students will use the idea that sound is vibrations in matter and create a light show that illustrates the physical interpretation of volume and pitch.

Materials

• Juice/soup containers, with both ends removed
• Scissors
• Balloons
• Elastic bands
• Glue stick
• Silver sequins
• Flashlight

Motivation

Once you have established with the students that sound is the vibration of air molecules, it is time to really show them what that means. The sound viewer is designed such that it gives a visual idea of what different sounds look like. The juice can helps to intensify the sound around the balloon, ensuring that not too much sound disperses into the surrounding environment. The balloon, being stretchy, will feel the vibrations in the air that you produce with your voice, and will react to it by vibrating. Finally, the light that is bouncing off the attached sequins will also vibrate, and the motion of the light show will vary with the qualities of the sound that you make.

The point of ambiguity in this activity is that to keep things simple, the descriptions that the students produce of the movements of the lights need not be quantitative in any way. However, this can sometimes lead to confusion. To avoid this, get the students to do each kind of sound (the kinds specified on the worksheet) before writing anything in. After that is done, get them to rank speeds from highest to lowest, and get them to think about which sounds make individual light ‘dots’ move the farthest from their starting point.

Procedure

Part 1

First we need to build our sound viewer. First you will cut the mouth off the balloon. Then, stretch it over one end of the juice or soup can, leaving the other end open. To ensure that the balloon stays on, feel free to use elastic bands or tape to solidify it. Make sure that the balloon is nice and tight. Now, glue about 15 sequins (depending on how big they are) onto the face of the balloon which is outside the can.

Part 2

• Use the sequins to reflect the light of a flashlight onto the wall. Now, experiment with making different sounds and speaking words into the juice can and watching what happens to the lights on the wall.
• Using the provided worksheet, describe how these different qualities in the sounds you make affect the motion of the lights on the wall.

Investigating Questions

• Loud sounds are characterized by ________ vibrations
• Soft sounds are characterized by ________ vibrations
• High pitched sounds are characterized by ________ vibrations
• Low pitched sounds are characterized by ________ vibrations