Noise-Canceling Headphones: Gimmick, or Commuting Must-Have?

Pack a large number of people into a small, confined space, and you're bound to get noise. People talk, babies cry and engines drone — and all three combined is enough to drive any frequent commuter mad. Luckily, headphones are great for blocking such distractions out, but they too have their limits; there's only so much noise even Sonic Youth can drown out.

all external noise, but this is incorrect. Instead, their job is to filter noise. A built-in microphone on the outside of each ear cup samples ambient noise, which is then passed to a microchip on-board. Only consistent, repetitive waveforms — engine noise or construction work, for example — are removed from the final product.

A simple pair of Shure noise-canceling earbuds.

However, even this approach to noise cancellation has its limits. Most models work poorly with high frequency noise, because their waveforms change much more quickly than a low frequency sound. And because most headphones have limited audio processing capabilities, these faster waveforms are harder to deal with.

So are there any scenarios in which noise-canceling headphones are actually worthwhile? Any location with a droning, low frequency noise will benefit most from a fancy Bose, Shure or other-branded headset, though your mileage may vary. Unfortunately, those talkative teens on the subway each morning will still remain as loud as ever.

really looking for is a sound-isolating model. This type of headphone cancels noise in a very different fashion, blocking it in the first place. There's no microphones or electronic trickery required here — simply foam, rubber or other insulating material that conforms to the shape of a listener's ear, blocking outside interference.

With this in mind, what sort of noise-canceling or blocking techniques do your own headphones use? Do they work as advertised, or are such technologies simply marketing gimmicks?

Images via Flickr user jquiz, Shure, Boze.