Is It Possible to See Sound?

What does sound look like?

Sound can be described as pressure variations in the air. Through solids, it is transmitted via vibration. Since sound has fluctuations just like waves, sound is treated as a wave phenomenon. Sounds passes through solids and induces vibration which could be used to visualize the sound waves themselves. Cymatics is the study of wave phenomena and its visual representations. It is commonly used in the study of sound waves, as light waves are usually easier to see.Loudspeaker and Waveform

Conceptual image of sound waves.

The top image shows sound as a longitudinal wave with pressure fluctuations of air molecules. A simple way of thinking about this is to imagine a Slinky on its side. When one end is struck, you can see the compression travel along the length of the Slinky and oscillate back and forth until the wave loses energy. Sound does the same thing when it hits or travels through solid materials. The back and forth oscillation in solids are what induce vibration. There is a special class of waves that induces the most vibration and gives us a view of a wave’s most important characteristics. These are called standing waves.

A standing wave is formed when one wave bounces off of something and reflects directly backwards. Waves don’t always reflect perfectly like above, but for cymatic purposes, we’ll focus on ones that do. The maximum height of a wave (distance between lowest and highest points) dictates the amplitude. The higher the amplitude, the louder the sound, for instance. Nodes are points in which the amplitude is zero, and the antinodes are places where the amplitude is a maximum.

Imagine these waves passing through and reflecting inside the thickness of a plate of metal (or any medium). The points in which there would be the most vibration would be the antinodes. At these locations, the sand on the plate would move away to areas of less vibration – the nodes. When we factor in additional waveforms interfering with each other, the possibilities are endless. 

How are cymatic images made?

One method is to use a Chladni Plate. This is a metal plate hooked to a speaker. Sound playing through the speaker, and thus vibrating, induces the same vibration in the plate. Sand placed onto the plate shifts into place depending on the location of the nodes and antinodes of the sound waves. Other methods include using light and water (like the picture shown earlier). Some musical artists have decided to play around with this idea and make some interesting music videos (music video is near the end of the page).

Is sound really 2D?

2D waves are a simple way to conceptualize and graph sound waves, but a single sound wave is actually a 3D shape propagating from the source of the sound. This may seem to contradict the wave interpretation, but it doesn’t. Fundamentally, whether it be sound or electrons, waves are 3D.

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