> As the string vibrates, the air molecules around it bounce to and fro, creating a wave of jiggling air molecules that we call sound. If you could watch the ai

> As the string vibrates, the air molecules around it bounce to and fro, creating a wave of jiggling air molecules that we call sound. If you could watch the air carry out this periodic dance, you’d discover a smooth, undulating, endlessly repeating curve that’s called a sinusoid, or a sine wave. That's a remarkably poor description, I think? It could make a young reader imagine the sine graphs are there in the air, but very hard to see. I guess to construct the wave you'd do something like measure density changes at a single point in space?