Earmark, maker of audio trainers for educational use, makes a hearing
protector incorporating noise cancellation technology. The unit also
incorporates a transmitter/receiver for two way communication. This
device is normally used in a high noise industrial setting where
communication is vital. This device is fairly expensive.
I also know of a company who makes a device for sound field use that uses
cancellation technology. This device is also used in industrial and
The technology incorporated in both of these devices is most effective in
cancelling steady, repeating noise at low frequiencies like air
conditioning noise, pumps, engines. I am not familiar with high
I have heard people complain about disorientation while wearing noise
cancelling headphones when moving. I suppose that since the cancellation
signal is generated from a microphone on the headset, and this signal
changes in relation to the head, and there is a time lag between movement
and compensation, this combines to create some confusion. I'll leave
that to a psychacoustician to explain.