Noise cancelling headphones use special electronics to cancel outside noise. They are designed specifically to block constant, low frequency noises, and are excellent for planes trains and automobiles.
For the consummate road warrior, noise cancelling headphones can be an oasis in the chaos of frequent travel.
Noise cancelling headphones provide approximately -15dB ~22dB of isolation, mainly in the lower frequencies. The circuitry excels at filtering out low-pitched, constant sounds like airplane cabin noise and train rumble but do not attenuate much over 1,500 kHz, so high-pitched street traffic, loud talking or the hollering kid behind you may still penetrate your blissful listening cocoon.
They typically employ a noise-cancelling switch and are battery-powered (most have AAA batteries that can be replaced on the road).
Many upper tier models are of high quality construction, precise fit and finish, with an attention to comfort and luxurious accessories such as high quality carrying cases.
A downside is that noise-cancelling electronics adds a premium to the cost, while all those added electronics can have some degradation of sound quality.
Bottom line? We recommend noise cancelling headphones specifically for airline, train, or bus travel, but for many other noisy environments a closed headphone or an in-ear headphone can potentially block more sound and can deliver better sound quality for the price.