You might want to try http://www.nct-active.com
I visited them years ago as a small start-up and wrote about them. They had a patent on a microcomputer-based system that relied on sampling the source frequency of noise (such as a spinning fan rotor), then generating the cancellation anti-noise within that narrow band. Not sure if they're still marketing the basic computer unit; they've branched out into ultra-thin picture-type loudspeakers and other hardware.
If you'd care to make your entire listening room 'disappear' through cancellation technology, contact Cambridge Signals Technology in Cambridge, Mass., and buy a Sigtech 2000 for $6k plus.
--John
[This message has been edited by John Mason (edited 11-27-2000).]
I visited them years ago as a small start-up and wrote about them. They had a patent on a microcomputer-based system that relied on sampling the source frequency of noise (such as a spinning fan rotor), then generating the cancellation anti-noise within that narrow band. Not sure if they're still marketing the basic computer unit; they've branched out into ultra-thin picture-type loudspeakers and other hardware.
If you'd care to make your entire listening room 'disappear' through cancellation technology, contact Cambridge Signals Technology in Cambridge, Mass., and buy a Sigtech 2000 for $6k plus.
--John
[This message has been edited by John Mason (edited 11-27-2000).]