miércoles, 30 de enero de 2013

Quartz Cantabile


The quartz cantabile is a new musical instrument that applies a method known to thermoacousticians for converting heat into sound. The phenomenon occurs due to the introduction of a strong temperature gradient across a tube closed on one end. A ceramic honeycomb material called the stack is placed in the bottom half of the tube. The stack allows air to pass through its many channels, but does not conduct heat. When extreme heat is introduced to the closed end of the tube, the air in this section expands, pushing through the stack, where it comes in contact with a relatively cool section of the tube. The air then contracts, pushing back towards the hot end where it again expands. This completes one oscillation, which in succession set up a standing wave in the tube, with the frequency dependent largely on the length of the cylinder. The resulting tones are loud and pure—perhaps the purest occurring in nature, with strong fundamentals and relatively few overtones.


The instrument consists of 15 bunsen burners, attached in series to a small propane tank. While the 25 tubes span a range of two chromatic octaves (from A 110 Hz to A440), each burner powers only one tube, and the scale of the piece being played determines which 15 tubes will be operating at a given time. By grinding a small hole in the closed end of the tube, one can easily play each tube by covering the hole to activate the oscillation. Due to the instrument's extreme sensitivity to heat input and other atmospheric conditions, precise tuning is nearly impossible. However, this has a surprisingly positive affect on the quartz cantabile's musicality—strong beating occurs as multiple tones shift in and out of phase with each other, giving the instrument a rich and unique timbre.

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