What a beautiful noise

Noise-cancelling headphones and sound-isolating earphones make travel a lot more enjoyable. Michael Dervan takes to the sky to test the new technology

It's one of those wonderful, mad-scientist kind of ideas that modern technology has turned into a reality - battery-powered headphones with circuitry that actively counteracts the noise around you.

The benefits are clear. You can listen to music in noisy places where otherwise you might find yourself turning the volume up to hearing-damage levels. And protection from high noise levels while travelling - by plane, train, car or ship - can significantly reduce your level of fatigue.

In reality, of course, not all extraneous noise can be excluded.

Yet, when I first put on a pair of Bose QuietComfort 2 headphones in a fairly quiet office and flicked the On switch, the effect was magical.

Both the ever-present computer whirring and the low rumble of traffic outside the window seemed to be sucked away. I thought of Aladdin disappearing down the spout in a spiral of cartoon vapour. All that was left was the softest of hisses.

The noise-cancellation is most impressive at low-frequency challenges, such as taming the roar of a jet engine. With no music playing, normal conversation is still possible, though voices sound quieter, as well as lighter and thinner in tone.

At £285 (€417) - Bose's Irish website does not quote a price in euro; the US price is $299 - Bose, who first turned a piece of flying crew equipment into a consumer product, represent the luxury end of the noise-cancelling headphone market. The ergonomics are well-nigh perfect.

Softly-cushioned earpads fully enclose the ears, and the adjustable headband is also cushioned. I've tried a lot of headphones in my time and these are among the most immediately comfortable and secure I've ever worn.

The major competition comes from Sennheiser, whose foldable PXC 250 is smaller and lighter. Also, at €149.95, it's considerably cheaper and more readily available - Bose concentrates on mail order and internet sales. There's a separate battery unit on the connection cord (it can be clipped to a belt), yet the Sennheisers fit into a pouch less than half the size of the one needed for the Bose. The hiss of the processing circuitry is rather more noticeable, and the earpads are small, sitting directly on the ears rather than fully enclosing them.

Sound-isolating earphones approach the noise challenge from a different direction. Think of them as good, old-fashioned earplugs, adapted to channel the sound from a high-quality earphone directly into your ear canal.

The brand leaders are two Illinois-based companies, Etymotic Research (whose track record in the field goes back to 1984, and whose other lines include hearing aids, audiometry products, and high-tech earplugs), and Shure (best known for its microphones, and a major supplier of cartridges and styli for record players in the days of vinyl).

These products can be hard to find in shops, so the main avenue of supply is mail order or the internet.

I set off on two recent Dublin-London trips with a bagful of headphones and earphones, a smart new iPod (on loan from Apple Computer), and an old portable CD player to check out performance with a seriously low-output source.

On a modern Airbus, everything worked to perfection. The headphones cancelled enough of the cabin noise to make even quiet music fully listenable, and the sound-isolating earphones reduced the intrusions even more successfully. When I came to put everything away, the unmediated din of the cabin seemed like a dreadful intrusion. I even found myself wondering how I'd ever thought the plane a quiet one in the first place.

The second trip was on well-travelled Boeing 737s, and I sat behind the engines to expose myself to the maximum available roar. This experience eliminated the Sennheisers, whose earpad design allowed more noise leakage than the noise-cancelling circuitry could effectively counteract.

Paradoxically, however, I found myself preferring Sennheiser to Bose for actual sound quality. The Bose seemed too coloured with an artificial gloss and resonance which seemed optimised for movie soundtracks rather than music. And the Sennheisers still work when the batteries die, albeit at a lower volume level and with no noise-cancelling. A battery-less Bose becomes a comfortable ear-muff.

The clear winners, for both noise reduction and sound quality, were the sound-isolating earphones. The quality of these tiny products is remarkable. A quick listen to Shure's E3c - expect to pay around £125 (€183) - or Etymotic's ER6i (€118), both styled with iPod users in mind, may well find you redefining your idea of music on the move. Standard supply earbuds simply don't compare.

You could liken the experience to lifting a veil of fuzz, or sharpening the sonic focus in a way that mimics the improvement people experience when they get the correct glasses after a proper eye test. And, as with the right glasses, you'll find that fitting them comfortably works smoothly in no time at all.

Shure's dearer and cheaper models - the E5c, £325 (€476) and E2c, £60 (€88) - are bulkier, less easy to fit, and more obtrusive to wear. The E5c boasts two driver units for each ear and is capable of astonishing volume levels. You may have thought that no earphone could ever create the illusion of room-shaking tremors. The E5c pulls off that feat. Bass freaks will adore what's on offer, but in purely acoustic music - which includes the bulk of the classical repertoire - the effect is less successful.

My favourites among the earphones both came from Etymotic's upmarket ER4 series, which boasts the best sound isolation among all of the products I sampled. The ER4P (€229) is designed for portable use, and though I'm usually a purist when it comes to sound reproduction, I thought the contouring of the frequency response was a definite bonus in noisy environments.

At the same price you can have the ER4S, intended for home stereo systems rather than portable music players. It needs a higher-output source, dispenses with the enhanced bass, and provides highly analytical, timbrally truthful sound. At some cost (€59.95) you can buy a conversion cable to transform the P model into an S, and have the best of both worlds.

Sound-isolating earphones need to be fitted snugly into the opening of your ear canal, and the seal with the outside world is important for both sound isolation and bass performance. The earphones all come with a range of differently sized and shaped removable sleeves, and they all have arrangements via filters or cleaners to prevent blockage by earwax.

Sealing off your ear has side effects. It magnifies perception of your own body noises - especially breathing, and chewing or other jaw movements - and the cables close to the ear transmit noise from friction with your clothes. Shure's solution is to trail the cables tightly around the back of the head. Etymotic offer a shirt-clip for the front. I wouldn't recommend serious physical activity for anyone wearing these earphones, though listening in bed is no problem, once you don't fall asleep while they're still in.

In the past, I've avoided earphones and headphones in planes and on trains, for fear of damaging my hearing. Sound-isolating earphones offer a quality of reproduction and a level of protection to change that. I may even have to buy an iPod.