Vix

We've been following the quest for the world's best speakers for some time but remarkably, there's still room for improvement. A key issue that plagues proper sound reproduction (and thus its perceived quality) is a phenomenon known asdeconstructive interference. This occurs when audio signals overlap and cancel one another out, creating dead spots which, until recently, have been very difficult to track. Now, a team from Britain's National Physical Laboratory (NPL) has figured out a clever way to make speaker sound "visible" - and they do it with laser light.

"Speakers are very common in modern life, whether it's for entertainment, communication or safety," observed NPL team leader Ian Butterworth. "And you've probably noticed the loudness of sound you hear coming from a loudspeaker is likely to vary depending on position. At low frequencies, most speakers are pretty even, which is termed omnidirectional. But at high frequencies they become much more directional- we've much stronger radiation in certain directions."

Listeners sitting behind or to the speaker's side often detect a fall-off in the higher frequencies. In previous efforts to reduce or eliminate this directionality, speaker designers resorted to the time-consuming task of placing a microphone in several positions to map out the dead spots. The NPL team saw this as an opportunity to make a big difference in the way new speakers are designed....