This story really appealed to two of my passions, gadgets and high-quality audio. Etrema is an Iowa-based company that is a spinoff from the U.S. Department of Energy lab of Iowa State University. The company has developed products made with a "smart" metal that can turn your walls or your head into speakers. The smart metal in all of Etrema's offerings is something called Terfenol-D, a metal that changes its shape--as quickly as 20,000 times a second--when exposed to a magnetic field. A tiny amount of the metal--about a splinter's worth--causes invisible vibrations that are rapid and powerful enough to move the surface of an entire tabletop, allowing it to transmit sound.
Terfenol is currently thought to be the "smartest"--i.e., the most reactive to its environment--metal in the world. And for the time being at least, the 40 employees of Etrema are the only people in the country who know how to affordably manufacture it. Terfenol is a combination of terbium and dysprosium, two rare earth metals, and was developed by U.S. Navy engineers at the Naval Ordnance Laboratory in Washington, D.C.
This is one of the most exciting tech audio developments I have seen in quite awhile, and I am quite certain I will be purchasing some of their products in the very near future. It appears likely that they will have less expensive products in the near future, but if you can't wait till then you can go their site to review their products.
Fortune November 10, 2003 page 195-196