Undeniable Friday: The Sands of Chime

Friday, August 25, 2006

It's Undeniable Friday! Every Friday, in addition to an odd little factoid, UndeniableFacts.com gives you a fun puzzle, illusion, or activity to enjoy and share.

Today: The Sands of Chime

The effect:
A sound is played below a drum with musician's sand on it, and within 30 seconds, strange patterns and shapes appear on the surface of the sand.

(Because of the high compression used by revver, some subtleties of this effect's beauty are hard to see in the video)
Zipped Version

The setup:
This experiment requires musician's sand, which is a carefully regulated mixture of consistently sized granules of quartz and graphite. It is used primarily by soft-shoe dancers and for rain sticks. It is also, to a scale factor, extremely similar in specific density to the outer crust of the earth. Musician's sand can be found at most music stores, and occasionally at nurseries.

You'll also need a snare drum and a guitar or bass amplifier. The set up for this experiment is fairly simple: place the snare drum on the amplifier, pour the sand evenly over the snare drum, and play different frequencies through the amplifier. Make sure to disengage the snare.

Many different sound waves will work for this experiment, but here are a few (the ones used in the video) to get you started.


Keep in mind that sound volume is not the only important factor. If the sound hurts your ears, it's too loud. Also realize that if the sand is uneven, there will be distortions in the patterns.

The explanation:
Because of its specific density, musician's sand carries sound adiabatically; it rearranges itself to absorb the energy from a sound wave, rather than emitting the energy as heat. The result of this is that specific frequencies of sound can be used to create patterns in the sand.



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