In Depth
Technology
How it works: Noise-cancelling headphones
How high-tech headgear eliminates unwanted sound
October 10, 2007
By Chad Sapieha | CBC News
Technology is at its best when it appears to work like magic, and that's exactly what noise-cancellation headphones do. Place a set on your ears, and the sounds of the world outside simply disappear.Panasonic's RP-HC500 noise-cancelling headphones. (Panasonic Canada)
At first you might be inclined to think that the headphones' snug ear cups simply block outer sounds. To an extent, you'd be right — much like quality traditional headphones, noise-cancelling models (both headphones and fitted ear buds) tend to have good physical sound barriers that help to block outside noise. But this blockage is passive and has nothing to do with the dynamic eradication of unwanted sound.
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http://www.cbc.ca/news/background/tech/how-it-works/noise-cancelling-headphones.html
(This sort of handy devices work almost like a magic! I've been amazed by them. They won't aggravate the potential situation of hearing loss due to very loud sounds or music. Unlike traditional headphones, they quieten the ambient noises instead of simply encouraging you to increase and increase the sound volumes of your headphones. When are they going to become cheaper so that I can buy one pair and don't feel the pinch in my pocket? --double_take)
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