Different musical instruments work because they play the note you want to hear. This seems obvious, but it’s no small thing to make something play exactly the right note, and leave out all of the other noise. How do they do this?
Instruments are made from lots of different stuffs and geometries. Some things, like violins and guitars, use tight strings to create their notes. Tuning forks and the reeds of a harmonica use vibrations of solid materials with specific lengths. Other instruments, such as organs and clarinets, produce the notes in a tube of air. That’s the kind of instrument I’m playing with here, except my tube is a simple piece of pipe.
You might not have a tuning fork to create this phenomenon, but is there something else you could do to make a tube sing? What other instruments could you create? What do you think the sound waves in the tube look like?
On a camping trip a while ago, we had a site that overlooked a small, calm lake in the Uintas. From a perch we could toss small rocks into the lake and watch the ripples they created. Tossing two rocks at the same time made it so that we could see what happens when the two sets of waves overlap.
You might want to look at the video up close, or even pause it at certain spots to see what’s happening. What do you observe? What patterns do you notice? Where else could this happen?