Roy Kornbluh at SRI International in Menlo Park, CA, is developing the loudspeakers of tomorrow-which look a lot like the plastic wrapping that the speakers of today come packaged in. Kornbluh treats silicone with an electrically conductive grease that makes it expand and contract when charged. Sending electric signals through a thinly stretched sheet of the stuff causes vibrations, thus generating sound waves.Light, flat and flexible, the silicone speakers could be applied to surfaces that conventional speakers would be too bulky for-for instance, they could line a car’s interior roof. And because sheets of silicone are easy to fabricate, doubling or tripling their size should add only a few cents to their production cost; eventually it may be possible for them to cover entire walls in your house. SRI says it has already built speakers that can passably reproduce a symphony; a version that matches today’s highest-fidelity speakers is probably about three years away.