How it Works: A TV Speaker That's Almost Paper-Thin

Loud and realistic sound without the separate stereo system

Flat Notes

A 0.02-inch-thick plastic sheet, made of the same material as water bottles, vibrates to produce sound Clamps hold the sheet's center still so the two sides vibrate independently to create stereo sound An amplifier and signal-processing chip are placed alongside a flat-screen TV's other electronics A 0.2-inch air gap separates the sheet from the TV screen so that it can flex freely One to eight piezoelectric motors on each side of the sheet control its fine movements The TV's ordinary bezel hides the motors built behind itPaul Wootton

You don't need big speakers to get big sound from your television. Emo Labs's Edge Motion pumps tones out of a vibrating plastic sheet, just two hundredths of an inch thick, that sits over a TV screen. Its wide surface produces louder and more realistic sound than the small speakers in most TVs, but it takes up a lot less room than a separate stereo system.

The plastic sheet projects Conan's voice, American Idol's music or any other sound by flexing in and out in different patterns — fast, slow, shallow, deep—to release waves of various frequencies and volumes. The movement is so minute and quick that it's imperceptible to the eye. It's precisely controlled by tiny, quiet motors made of a ceramic material that automatically expands when jolted with an electrical audio signal. The system reproduces all tones except the deep bass notes usually handled by a subwoofer, since that would require large, visible pulses.

Expect Edge Motion to be built into some TVs next year, adding 10 to 15 percent to the cost. Laptop screens will start singing soon after.