A few years ago, if you wanted a pair of good noise cancelling headphones, you'd have had to put up with wires getting in the way and quite a bit of weight compared to modern headphones. These days there are plenty of light-weight, wireless options that come in all different shapes and sizes, from big over-ear cans to small true wireless ear-buds.
When it comes to reducing the amount of external noise that reaches your ear, there are two main types of technology – noise isolating, and noise cancelling. Noise isolating headphones (also known as passive noise cancelling) simply limit the amount of noise that's able to reach your ear using the materials that they're made from. Noise cancelling headphones (also known as active noise cancelling) are the more sophisticated of the two because they listen to the external noise and cancel it out using some very clever science.
Before explaining exactly how they work, it's useful to understand that all sound has a particular pattern, usually visualised as a wave, noise cancelling headphones work in a very clever way to cancel out that external sound wave. They have a microphone on the outside of the headphones that listens to the noise around you, then the headphones process the pattern of the noise, and play the exact opposite pattern inside the ear-cup to cancel it out. This noise cancellation doesn’t affect your music because the headphones are only listening to the noise outside the ear-cup.
Noise cancelling headphones are very good at blocking persistent noise like crowds, traffic, or the constant rumble you get on a train. But they're not quite as good at blocking random noises because the headphones take time to hear the noise, process it, then play the correct signal to block it. This might only take a few milliseconds but by that time, it's already managed to get through the ear-cup to your ear. It's all a matter of processing power, so as the technology behind noise cancelling improves, so will its ability to block different types of external noises.
It's safe to say that noise cancelling headphones pack in the most technology, but that doesn't necessarily mean you'll get a better listening experience. It all depends on the headphones themselves, and where you’ll be using them. Some high-end noise isolating headphones offer excellent sound deadening thanks to how they’re built, and the materials used, but this generally means they’ll be a bit heavier than their high-tech counterparts.
If you'll be using your headphones in a noisy environment like busy city streets, in the office, or on a plane, noise cancelling is probably the way to go. On the other hand, if you’re looking for that perfect analogue audio experience and you don’t want any fancy electronic trickery messing with your ears, you might want to go for a good pair of noise isolating headphones.
That’s not to say you can’t have the best of both worlds, some high-end headphones offer excellent noise isolation and also include noise cancelling technology. So you can use them as standard headphones when it’s nice and quiet, but when things start to get a bit loud, just switch noise cancelling on.