Wednesday, January 31, 2007

ice chime workshop

I spent most of the weekend working on ice chimes. After a serendipitous discovery during the 2006 competition, it seemed that it would be fairly easy to make rectangular chimes out of ice. Unfortunately, it has been hard to improve upon the original, lucky design. Although it is difficult to produce large blocks of ice in Colorado's climate, recent weather has made it easy to produce slabs of ice by freezing water in shallow, cardboard boxes lined with garbage bags.

I had hoped to be able to make rectangular bars of ice attached at one end, but it has turned out to be difficult to get good tones that way. I've had better luck with bars that are free on both ends and attached about a quarter of the bar length from each end, like the bars on a xylophone. In fact, our music box will probably end up sounding quite a bit like a xylophone.

I made chimes of varying shapes and sizes and digitally recorded the tones they produced. Some handy, open-source software made it easy to analyze the spectrum produced by each chime. With bars free on both ends, the chimes produced tones as expected according to various sources identifying Young's Modulus for ice.

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