Performance Probably the biggest compliment I can pay the NC is that it doesn't sound like an active noise-canceling headphone. What I mean by that is that you usually give up some sound quality whenever you move to a model that runs your sound through noise-canceling circuitry. You tend to lose a bit of clarity, which is evident with headphoned like the Monster Inspiration, which come in "passive" and active noise-canceling versions (the passive version sounds cleaner).
In fact, when I handed the headphones to CNET contributor Steve Guttenberg, who does many of our reviews of the higher-end headphones, he at first wasn't sure the noise canceling was on. When I told him it was, he was impressed. Steve's not a big fan of noise-canceling headphones, but he thought the Harmans sounded good.
To put it another way, for an NC model, the Harman sounds comparatively natural and accurate. It has a sound profile similar to that of the CL, which is considered a balanced, more neutral set of headphones that doesn't overaccentuate the bass or treble. Still, like that model, the bass here is plump and pleasant (it seems to be a touch more plump than the CL's) but not overreaching. Like with the CL, there's a bit of restraint in the treble, so you're not going to get that edgier detail of "faster," more aggressive headphones that push the treble harder. I wouldn't call these laid-back, but they're fairly warm and I tried them out with a variety of music and came away feeling that they were quite versatile. That said, if you're someone who wants faster headphones that can deliver a more thumping bass, the Monster Inspiration would probably be a better choice.
I liked the sound of the Harman NC slightly better than that of the Bose QC 15 and Audio-Technica ATH-ANC9, both of which are very good for noise-canceling models. The QC 15 has a touch creamier, smoother sound. The Harman seems a tad more dynamic (compared with the Audio-Technica as well). That said, the Sennheiser Momentum, which retails for $350, delivers clearer, more detailed sound than any of those models, though it isn't as comfortable. And Audio-Technica's $160 ATH-M50 also offers more detailed, dynamic sound for about half the price. But both the Momentum and ATH-M50 leave off the active noise cancellation.
So what happens when you turn off the noise-canceling on the Harman Kardon NC? What do the headphones sound like?
Well, they sound more subdued. Like with a lot of these noise-canceling headphones, when you turn on the NC, the bass gets a boost and everything plays louder. But I was perfectly happy listening to the headphones without the NC on (Harman calls it "passive playback") and simply raising the volume a notch. What's nice is that you have the choice between the two modes.
In the case of the NCs, Harman engineers have done a good job with both the noise cancellation itself (there's only a very minimal hiss when you sit in silence) and the digital processing. I didn't take these on an airplane, but I wore them on the streets of New York and on the subway, where there's a lot of ambient noise. The NCs didn't shut it all out, but they did a decent job muffling the sound. Comparing it with the Bose or the Audio-Technica, which has different noise-reduction settings for different environments, I thought the Bose QC 15 was the best, with the Audio-Technica a close second, followed by the Harman.
If you're wondering how the $112 Monoprice compares, I'd say it's close to the Harman in terms of how effective the noise canceling is. But in terms of sound quality, while the Monoprice doesn't sound bad at all, it's a step down from all these more expensive models -- particularly as far as clarity goes. It also doesn't have the build quality or quite the comfort level. Of course, it costs nearly one third of the price, which makes it a relative bargain.
Conclusion The Harman Kardon NC offers excellent sound quality for a pair of noise-canceling headphones, with an impressive fit and finish. This model arguably sounds slightly better than the Bose QC 15 and Audio-Technica ATH-ANC9, two other $300 noise-canceling models.
It also offers the advantage of having a built-in rechargeable battery and includes an inline Apple-friendly three-button remote/microphone for making cell phone calls (Bose doesn't include such a cable with its QC 15s).
My only reservations about them concerns their design. While it's distinct and eye-catching, it won't appeal to everyone, and the headphones are heavier than the QC 15 and Audio-Technica ATH-ANC9. The Harman NC is quite comfortable, but Bose remains the clear winner in the comfort department.
In an ideal world, of course, you'd get a chance to try these before you buy them and compare them with competing products. The alternative is to try them and return if you don't like them (stores like Crutchfield have a 60-day money-back return policy). I think most folks will like them a lot, but each person's ears and head are different, so there are no guarantees. Still, as far as noise-canceling headphones go in this price range, the Harman Kardon NCs are definitely worth strong consideration.