As with all noise-canceling headphones, NoiseGard achieves this by taking in the ambient noise with an external microphone, inverting the signal and feeding it to the listener, effectively blocking the unwanted noise from the listener.
These headphones are made from hiqh-quality components, including an improved microphone and algorithm dubbed NoiseGard 2.0 effectively attenuating noise by as much as 23 dB (around 90%). Because of the earpad design, some noise-cancellation is done passively by physically isolating the listener from the outside environment. The active noise-cancellation feature can be toggled on and off, and requires 2 AAA batteries to operate (included).
Mounted on the rear earcup are a set of volume controls, a noise-canceling on-off button, and a TalkThrough button. Using the TalkThrough function allows you to quickly hear what is going on in your immediate environment without removing your headphones. The microphone picks up and sends all environmental sound to the headphone drivers.
As with most Sennheiser-made headphones, they fold flat for easy storage. The over-sized earcups will fit almost any one, but may be considered cumbersome. Also included in the package is a zippered transport case, an airline double-mono in-flight entertainment adapter, a 1/4" adapter.
Weight: 8.46 oz (240 g). Maximum SPL: 108 dB
Compare to the Audio-Technica ATH-ANC7 and the Bose QuietComfort 3 noise-canceling headphones. The PXC 450s are available for around $450 and were first made available in June, 2007.
