Introduction

Imagine you could point sound the same way you can point light with, say, a flashlight. Suppose speakers existed that could send focused beams of sound wherever they were pointed. You could speak into a megaphone and send the sound to a single person. Or you could have five types of music playing on the same dance floor. You wouldn't have to worry about turning your music down at night to keep the neighbors happy, so long as you didn't point it in their direction.

Thanks to recent advancements in audio engineering, this kind of product may soon be a reality. Researchers have discovered a way to project acoustic waves as a thin beam of sound: step into the beam, and the projected sound fills your ears; step out again, and you hear nothing. This new technology has sparked the interest of everyone from the U.S. Military to U2's Bono (Gartner, Feb. 21, 2002). In the next few pages, we will see how directional sound technology works and explore how it might be used in the near future.