As any frequent flyer knows, apart from industrial-strength knockout pills from a cooperative GP, noise-cancelling headphones are the best thing since eye masks and knitted slippers for the long-distance traveller. Not only do their noise-cancelling circuits make it far easier to hear movie soundtracks and music broadcasts but they also make it easier to drift off to sleep, by removing the intrusive drone of plane engines and air conditioning.

Of course, headphones of this type needn't be restricted to use on long-haul flights, they can be just as handy on trains and buses or in any other noisy environment. The Philips SBC-HN110 headphones have been designed with just this idea in mind. They sport a retro-cool look, are lightweight, fold up to next to nothing and come with a handy, soft carry pouch. A 6.5mm adapter is also provided for hooking into home audio gear and a two-pronged aeroplane adapter is included as well. A single AAA battery provides the power for the noise-cancelling circuitry.

Although the SBC-HN110s feature a circum-aural design, in that the ear cups completely enclose your ears, they are also open backed, with a grille on the speaker drivers to vent sound freely. Open-backed designs tend to sound better than similarly priced closed-back designs because the vent stops your sound from becoming congested due to pressure build-up on the driver.

We found the Philips easy to adjust, but the oblong shape of the ear cups didn't fit over our ears that well and once on we noticed that they didn't block much noise at all. It may be that they are a little flimsy for the job they are meant to do. Another niggle is that the on/off switch for the noise cancelling circuit is a major pain to locate and use when the headphones are on.

Putting our initial concerns aside, we hooked the headphones up to Perreaux's Silhouette SXH2 headphone amplifier to see just what kind of sound they were capable of. On simple pop tunes from Everything But the Girl they performed well, delivering a lively sound with clear vocals. Moving on to some Ben Harper tunes with more complex instrumentation, they sounded slightly muddier and their response a little slow. Bass was also a bit lacking and this was exacerbated on some bass-heavy offerings from the Black Eyed Peas, where the bass also began to distort.

Still, there isn't much ambient noise indoor, so we hooked up the headphones to our iPod and ventured outside. Noise-cancelling circuits work best against constant low-pitched sounds that they can set up an opposing frequency to and thus cancel out, but with the Philips not only did we notice a very obvious hissing sound, but there wasn't much success cancelling noise. Determined to be fair, we moved back inside to the laundry where we turned on the dryer. This is just the kind of low-pitched droning noise the headphones are designed to cancel but it just wasn't happening to any significant extent.