The purpose of this exercise is to show students the waveform representation of audio, and to add a fun exercise on top of it. When you record audio, it will show up as a plotted waveform below. You can then play it back in reverse. A fun challenge is to then open this in a new tab and try to match the sounds of the reversed speech, and see if the reverse of that sounds like the original.
For context: I used to play this game for fun all the time with my friend Brendan Sellers when we were messing around in his recording studio.