Group test: Noise-cancelling headphones pt2

Overview Price: £300 More info: Sennheiser Accessories: Carrying case, airline adaptor

Sennheiser PXC 450
The PXC 450 headphones are expensive, rather large, and a bit fiddly at times, but they certainly deliver the goods in terms of sound quality.

Sennheiser developed its NoiseGard noise-cancelling technology to protect airline pilots from engine noise, and the PXC 450 'phones do a really good job of cutting out background noise. You can hear the noise around you drop dramatically as soon as you press the 'On' button - and the results are equally impressive when you turn on your music player. The PXC 450 probably has the best overall balance between the higher and lower frequencies, producing a crisp, clear and clean sound that works well with everything from classical music to rock. Our only complaint here is that we really would have liked a bit more volume - even though Sennheiser do go to some lengths to warn you against having the volume turned up too high.

They're also nice and comfortable to wear on long journeys, with plenty of soft padding on both the earpieces and headband. We do have a few small complaints, though. The collection of control buttons on the earpiece can be a bit awkward, and you have to completely remove the headphones in order to reach the switch that turns the NoiseGard option on and off. And, despite the £300 price tag, Sennheiser don't even provide a rechargeable battery. However, many people will overlook these omissions simply in order to enjoy the excellent audio quality provided by the PXC 450 headphones.

Overview Price: £269 More info: Sony Accessories: Carrying case, airline adaptor, mains adaptor, battery pack

Sony MDR-NC500D
Sony claims that the MDR-NC500D is the world's first set of digital noise-cancelling headphones, and that they can eliminate up to 99 per cent of background noise. Of course, the 'up to' part gives Sony a bit of an escape clause, and we seriously doubt that the actual figure is anywhere near 99 per cent.

However, we can't deny that the noise-cancelling features do work very well and damp down background noise quite effectively. We also like the fact that there are three different noise-cancelling modes available, designed to cope with the different types of noise experienced on planes, buses and trains, and office environments.

The sound quality was pretty impressive too, producing a very clear, yet full sound on the higher and mid-range frequencies. Our only complaint is that the bass wasn't always as pronounced as it could be - bass guitar tracks in particular have a tendency to fade into the background if they're not pretty high up in the mix.

The headphones will run for about 15 hours using the built-in rechargeable battery, and there's also a separate battery pack that lets you run them for another ten hours off two AA batteries if the main battery runs out. The slight weakness in the bass output is a little disappointing, but the MDR-NC500D is still a good option for anyone that likes to wallow in music when they're travelling.