Seeing Music

This is a video I made while working at the Exploratorium about how the "Pendulum Snake" exhibit lets you see patterns that your ears hear when you play a chord. It's pretty sick.

To clarify what's going on:

A major chord is composed of the first, third and fifth notes of a major scale. The third of a major scale is 1.25 times the frequency of the first while the fifth is 1.5 times the frequency of the first.

The three pendulums Emily and I swung were designed to make 16, 20 and 24 oscillations in 30 seconds. If we imagine that the 16 pendulum is our root note (the first note in the major scale), then the 20 pendulum oscillates 20/16 = 1.25 times as fast, so it represents the third. The 24 pendulum oscillates 24/16 = 1.5 times as fast, so it represents the fifth.

When you play all three notes together on an instrument, it sounds really nice to the human ear and is called a major chord. When you let go of all three pendulums at the same time, it looks really nice to the human eye because you can see clear patterns of the balls lining up with one another at regular intervals of time. In the same way, patterns of air pressure waves (in this case, three of them) lining up with each other at regular intervals sounds good to our ears and is the physical basis of what musicians call harmony!