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Flat loudspeakers made from thin films of rubber bubbles have been developed
by engineers in California. Roy Kornbluh and his colleagues at SRI International
in Menlo Park made use of electrostrictive silicone, a rubber that expands or
contracts in an electric field. Varying the voltage across the films, which are
just 0.1 millimetres thick, makes the bubbles pulse in and out, producing sound.
Unlike rival flat designs, these speakers do not need drivers to push a
diaphragm in and out. At the moment, the speakers produce only high-pitched
sounds. But Kornbluh believes larger bubbles in some areas will be able to
provide the bass.