Denon’s AH-NC800 headphones are active noise cancelling models. They come with two lengths of cord and a two pin adaptor for older-fashioned aircraft sound systems. They use one AAA battery for power (good for 40 hours, says Denon), and come with a nice carry case.
Their over-ear design actually provides considerable noise isolation absent the active circuit. The pressure from the softly-padded headband is gentle, but firm enough to keep the headphones in place despite a sharp shake of the head. The padding against the area of the head around the ears is equally gentle.
Oversimplifying a little, active noise cancelling headphones work by using microphones to measure the ambient noise, then inverting the wave of that noise and feeding it into the signal. The inverted wave destructively interferes with the noise, cancelling it out. Clever and simple.
The problem is that the electronics behind this can produce noise itself. These headphones didn’t suffer from that at all: switched on, but with no signal playing, they were utterly quiet.
The power switch has three positions: off, on and ‘Restorer’. This last is supposed to improve the sound of compressed music (like MP3). Of course, like all such things, it merely manipulates it without restoring anything. It seemed to boost the treble, reducing the accuracy of the sound.
The ‘off’ position was interesting in that, unlike some noise-cancelling headphones, they still worked. Even if your battery runs down you can still have sound!
I preferred the sound in this mode a little over that with the noise cancellation operating.
You couldn’t use it in this mode some MP3 players because the sensitivity was significantly lower, so the volume levels would be too low, but for high quality home use, I’d suggest you try this mode.
Not that the noise reduction mode produced poor sound. It was wide in frequency coverage and reasonably well balanced.