The headphones boast an upgraded filtering process that relies on a pair of noise sensors and sound-deadening ear pads. What's more, these headphones offer a noise-canceling optimizer that "tunes" the sound to your specific head. So if you've got long hair, wear glasses or have a lumpy noggin that prevents normal over-ear cups from sitting properly against your skull, this NC optimizer will account for that.
As conventional headphones, the MDR-1000Xs deliver high-resolution audio -- assuming you've got them hardwired to a high-fidelity source. When using Bluetooth to wirelessly connect them to your source device, these headphones use LDAC technology to transmit high-resolution audio. And even when listening to compressed music formats, the 1000Xs use Sony's Digital Sound Enhancement Engine to upscale the audio quality to near high-res quality.
At $400, the 1000Xs are a bit more expensive than other noise-canceling headphones with similar specs but they do offer a novel means of interacting with the world around you without having to ever take them off. The "Quick Attention" mode enables the wearer to instantly cut the audio- and noise-canceling functions simply by placing their hand over the right ear cup. This way you can take part in short interactions -- such as ordering coffee or listening to an announcement over the PA -- without actually removing the cans.
Conversely, "Ambient Sound Mode" allows you to hear the ambient conversations around you but not enough to impede the enjoyment of your music. What's more, these headphones use a touchpad on the right ear, allowing you to tap to play/pause tracks, swipe up and down to adjust volume or left and right to skip or repeat tracks.
I recently had an opportunity to listen to the 1000Xs at a demo and was very impressed by their performance. They dutifully shut out all conversations in the room, even when I wasn't listening to music. They nixed the low-level drone of a white-noise machine in the room and even quieted the traffic noise from San Francisco's financial district while I stood seven stories above the street on an open-air balcony. The headphones themselves were surprisingly light and fit snugly over my ears. Even without the noise cancellation, they managed to drastically reduce outside sounds. After customizing the noise-canceling system to my ears, you could hear a veritable pin drop inside my head, it was so quiet.
$400 is pretty pricey for a pair of headphones, even for those as capable as these. But if you travel a lot, have extra-noisy neighbors, or just really, really like your auditory privacy, I can see the value in them. The MDR-1000Xs will be available in October though they're up right now for pre-order on Sony's website. The headphones will come in standard black and grey-beige and include an airplane adapter, carrying case and various cables.