Cup Phone Challenge!
Did you know the earliest mechanical phones such as tin can phones can be traced back to the 1600’s? Before the telephone was invented, mechanical phones were used to carry short messages across fairly long distances just through vibration!
In this experiment, we are going to test how cup materials affect how well our cup phones work.
Learning Objectives/Opportunities
Build basic knowledge about how sound travels and how various materials can improve sound
Science process skills: observation & experimentation
Next Generation Science Standard
1-PS4-4.Use tools and materials to design and build a device that uses light or sound to solve the problem of communicating over a distance.
Let’s Begin!
Materials:
Plastic cups
Styrofoam cups
Tin cans
String
Hammer
Nail
Set-Up:
The purpose of this activity is to test which materials best transmit vocal vibrations. Since the engineering of the phone cups is not central to the activity and may be difficult for little scientists, we suggest adults make the phone cups prior to the activity. You can make one of each design and test each model as a class, or make enough cup phones for each partner group.
To make cup phones, poke a hole in the bottom of the plastic, styrofoam, and tin cups. You can do this with a sharp nail and a hammer. Tap the nail gently until a small hole is created.
Thread a piece of twine through the hole and make a knot in the string on the inside of the cup large enough that the string remains inside the cup even when pulled tight.
Directions:
Have your students pair up. Designate one student as the message sender and one student as the message receiver.
Have the message sender write down their sentence on their Cup Phone Challenge worksheet and then speak the message into the cup phone.
Have the message receiver write down the message they heard on their worksheet. Have students compare the differences between the two messages.
Repeat for each of the three types of cup phones.
Have students select the cup phone whose received message had the fewest differences from the transmitted message.
Discuss as a class. Take a quick poll by a show of hands which cup worked the best. Did one cup phone work the best for everyone or did each group get different results?
Science Background: Acoustics
Sounds are created through vibrations! When we speak into cup phones, the vibrations from our mouths get directed into the cups and then vibrate down the string connecting the two cups. The tighter the string, the better and further the vibrations can travel. The vibrations are then directed into the cup on the other end of the string and are amplified by the curved nature of the cup, sort of like our ears, allowing us to receive the message from our partners.
How well this sound travels depends on many factors including the cup material, like we tested here, as well as factors like string tension, string material, and the softness or loudness the original sound.
Experiment Extension!
In this activity, we explored which cup materials made the best cup phones. We could also explore which types of string best transmit the vibrations as well. You can select strings of different materials (wool, cotton, twine) or different thicknesses (thin vs thick) to discover how these variables affect how well the cup phones work!