01.22.2016
Written By: Aaron Schulzetenberg
Today we did a few experiments to visualize waves in general, and sound waves in particular. We prepared three experiment stations for groups of students to cycle through after a brief presentation introducing what waves are, what frequency and amplitude mean in terms of sound and how waves can interfere. First, we explored spatial interference of sound waves by playing the same frequency sound from two different speakers and trying to find the maximum and minimum points by listening closely for sound variations throughout the room. Next, we looked into what happens when two sound sources at different frequencies can interfere in time to create a beat frequency on top of the two sounds which sounds quite different than the two sounds played independently! Finally, we got a very visible (and exciting!) demonstration of sound waves in the Rubens Tube. A speaker played different songs into a long copper tube with holes drilled into the top with propane circulating throughout the tube. The holes were ignited and the sound waves made the flames dance like an equalizer! Needless to say, everyone was pretty taken with the Rubens Tube. I think providing a few more opportunities to visualize the sound waves would appeal to the students for the other experiments, including graphical videos showing interference as well as electronic means of measuring sound levels to make the concept of waves and interference a little more concrete.