Simply put, these Sennheiser are the nest noise-canceling headphones I've ever heard. Unfortunately, they cost $100 more than Bose’s top-of-the-line Quiet Comfort 3 and a full $150 more than Bose’s popular Quiet Comfort 2. That makes the NoiseGard mostly a luxury purchase.
A large but comfortable circumaural headphone set, the PXC 450 comes in a fairly slim and easy-to-pack black zipper case. The handy Talk Through function, which works only when the headphones are in active mode, mutes audio and activates an external microphone to pick up conversations- an excellent feature. The right ear houses volume controls, a Talk Through button, a power switch, and a single AAA battery. The left ear houses the detachable audio cable and normal/ bypass switch.
In a head-to-head comparison, the PXC 450 reduced slightly more ambient sound and eliminated more high-frequency hiss than either the Quiet Comfort 2 or 3. Sonically, the PXC 450 blows Bose away. Its sound quality makes for some of the most powerful-yet tight-bass I've experienced in a pair of headphones. I know the price is ridiculous, but these headphones sound superb.
Sennheiser PXC 450 Noisegard: $450