Sony touts 'world’s first' digital noise cancellation cans
Sounds good...
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Whether you’re hoping to envelop your ears in music, or just block out the sound of a screaming baby, Sony's latest cans could be the answer. The electronics giant claims to have released the world’s first pair of digital noise-cancelling headphones.

Sony's digital noise cancelling headphones: a world first?
Analogue noise-cancelling headphones significantly reduce background noise by picking ambient sounds up using microphone near your ear then inverting and playing this soundwave through the cans to cancel the annoyance out.

Four sound modes cut out 99 per cent of ambient noises
Sony’s 'phones do the sound-cancelling digitally in software, which the company claimed makes for more effective noise cancellation over analogue. Analogue noise-cancellation cans are typically 80-90 per cent effective. Sony said its digital version is 99 per cent effective.
Two 40mm drivers are hidden inside the headphones and will cancel noise for about 15 hours from the internal lithium-ion battery. AA batteries can also be slotted in if you run out of juice.
Sony’s MDR-NC500D headphones are available online now for $400 (£200/€250). They will be available in Europe shortly.
COMMENTS
in theory yes...
But reality is never that simple - the DSP chip needs to get the delay right (hence the 4 modes I suspect) and not introduce any noise of it's own while still catering for a wide dynamic range. 99% is hard to believe - although one expects the 'tag' to come down a notch some something that is such an old idea?
not exactly hard to do, mind you
to cancel out noises, one channel needs to have the waveform inverted. so, left or right channel would be inverted. This would cancel out everything. so, you have a mic on one side with a dsp that inverts the sound waves and throwing that into one ear. Then the headphones play whatever you want them to. pretty low tech actually

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