June 8, 2007
Clay Cracks the Cracked Kalimba Conundrum!

Les Clay of Montana won the CD for figuring out what is going on. In his words:

"The crack, near the center of the face of the kalimba, produces a second resonant frequency in the wood itself, separate from the resonance of the [air in the] box, which is determined by its internal dimensions. Similar to a panel in a slit drum, the wood is free to vibrate along the crack at a certain frequency -- in this case, that of the upper B flat tine. It can be dampened with finger pressure to produce a vibrato."

In fact, the crack gives us two large wings on the face of the kalimba which flap as they vibrate.

You can imagine that if the wood were just weakened rather than cracked, this particular vibrational mode would be damped, as some of the vibrational energy is diverted towards mechanical friction of these two "hinged-wings." (By the way, when I run my swamp cooler and the humidity goes up, the wood expands, and the crack narrows as the two wings touch - when this happens, the high Bb is actually absorbed, so I play outside during the summer!).

Next week - some mathematical equations relating tempo to delay timing.

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