We enjoy the music we listen to without wondering how it came to be. Why do certain note combinations sound soothing and others unsettling?

For such an ethereal seeming thing, we sure know how to skillfully use music to elicit strong feelings and manipulate emotions. It would seem that music is not ethereal at all, and is a manifestation of real physical properties and how our minds work to understand them.

The visual patterns you see here are known as Lissajous figures, named after the French mathematician who studied them extensively. He used light reflected off of small mirrors attached to vibrating tuning forks to literally see sound waves in action.

The particular sound patterns you see here were made using a variation of Jules Lissajous’ experiment. Plastic wrap was stretched across a bowl to act like a drum — a tuned resonator. Two sine waves were tuned to the ‘drum’ in order to make it vibrate sympathetically, with one sine wave staying constant while the other was raised and lowered in frequency. A laser pointer aimed a beam of focused light at the vibrating plastic membrane with the reflection cast onto a piece of paper.

The sine waves had to be played loudly through an amplifier in order to vibrate the ‘drum’ enough to make good patterns. The sound was literally shaking the room.

The idea for this experiment came from the Harmonograph book by Anthony Ashton and the Lissajous figures that can be seen using an oscilloscope. The difference here is that the patterns on this page were made using physically vibrating air and surfaces compared to the electronic version seen on an oscilloscope. Musical harmony is more tangible and real when you witness how these patterns can relate to the ear and eye at the same time.

The result is a direct visualization of what is happening between the two sine waves. The basic harmony of music revealed. Simple harmony — octaves, perfect fifths, thirds, and fourths — make simple patterns. Complex harmony — minor thirds, minor sevenths, and seconds — make complex patterns. It is easy to see why we find simple harmony more digestible because its patterns are easy to recognize and recall compared to complex harmony.

Notice how the really interesting moving patterns are not formed from the most exact tunings. Where there is a slight difference the patterns are still easy to understand, but are animated and seem to move in three dimensions.

•Sound Pattern Video #1
•Sound Pattern Video #2
•Sound Pattern Video #3