Space Phone (3B25.55) Location: 10-4L Concept/Purpose: Sound waves in a solid medium. Procedure/Explanation: The space phone is a commercially manufactured toy consisting of two funnel-shaped plastic pieces connected by a very long weak (low K) spring. Two students can stretch the spring all the way across the lecture hall and talk to each other via sound waves travelling through the spring. The intensity of the sound waves are not very high so the speaker needs to speak loudly.