In search of a ‘cone of silence’ that works

August 26, 2012 

Remember the “cone of silence,” the failure-prone gadget that livened up Don Adams’ old Get Smart show on NBC? Adams played Maxwell Smart, a secret agent who sometimes tried to give secret information to his boss, who would lower the clear plastic device over both their heads. The cone of silence was supposed to make their conversation inaudible to outsiders. The gag was that they could never hear each other but everyone else could hear them.

I’d like a cone of silence that really works, a distance-adjustable sound damper small enough to carry with me and flick on whenever I need quiet. I’d thumb it on whenever the guy next to me has his car speakers up loud enough to make my fillings vibrate. The next time I was in a restaurant trying to have a conversation and found myself drowned out by music – and conversation pumped even louder so as to be heard over it – my cone of silence would come to the rescue. And imagine what it would be like in closing down nearby cellphone conversations.

The problem is, the cone of silence is fiction. Sure, you can buy headphones that cancel external noise to some extent. Some are active headphones that actually erase lower-frequency sound waves by creating sound waves of their own, cancelling out the noise by being 180 degrees out of phase with it. That works, though at some expense in musical clarity, but the headphones work best with a constant background, like the sound of the engines on a plane trip.

Noise walls

Creating “anti-noise” is a lot harder when the noise is constantly changing. The state of California tried to set up a system of microphones and loudspeakers north of San Francisco some years back to use noise-cancelling technology to create a “noise wall” around a highway. Alas, it didn’t work because it lacked enough loudspeakers and computer processing to track the continuously changing flow of traffic. So while we can use noise-cancellation headphones to make long flights more bearable, noise cancellation doesn’t fly in most noisy situations.

In any case, my cone of silence, shouldn’t force me to wear headphones to make it work. And I’m getting to think I need one more and more. Seth Shostak, whose day job involves listening for faint radio signals in the effort known as SETI – the Search for Extraterrestrial Intelligence – recently sounded off about loud music. Led Zeppelin’s 1960s concerts hit 130 decibels at times, which turns out to be as loud as a pneumatic rock drill, and a 2009 KISS performance (I can’t bring myself to call it a “concert”) hit 137 decibels, five times more than Led Zeppelin.

Addicted to sound

Shostak is right: As a culture, we’re addicted to sound, and many restaurant owners obviously think that the louder their place is, the more popular it will be. The most that high-tech offers by way of relief are sound-isolating tools like Brown Innovation’s Sound Domes or Museum Tools’ Secret Sound. These systems use highly focused speakers that aim sound at a listener directly beneath them so that local noise pollution is eased. This works nicely at places like trade shows, where each booth seems to have a louder sound system than the next. When you’re under the dome you can hear the local pitch, but people a few feet away cannot. At the same time, loud surrounding sound is much diminished as long as you stay under the dome.

This idea, which is essentially a column of sound, is not in wide use, and in any case still delivers sound. I’m looking for the high-tech company that can deliver the sound of silence, cancelling or softening noise on demand through a device no bigger than a cellphone. Our cacophonous culture needs this far more than yet another tablet or smartphone option.

Paul A. Gilster is the author of several books on technology. Reach him at

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