Loudspeakers are bulky boxes you leave in your living room. Headphones are trim transducers you stick in your ears. These are the two options you have for playing music, computer sounds and radio broadcasts. Well, not quite. There's now the Olympia SoundBug too.

Although it doesn't describe itself as such, the SoundBug is a radically different way of making sound. Based on research from Hull University and involving a new material called Terfenol-D, this little device is neither speaker nor headphone; in fact it has no conventional cone at all.

About the size of a thick mobile phone, the SoundBug has a sucker like the ones you use to stick Garfield to the back window of your car. Stick the sucker onto any smooth surface, give the SoundBug a quarter turn to create a partial vacuum and the whole unit is firmly fastened. Apply sound and the device vibrates whatever material it's stuck to, making it into a speaker. It may only move a few micrometers, but it's a whole window, door or table that moves.

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The SoundBug is a sturdy metal and plastic unit which takes two AAA batteries, which last for a good while. The sound output is only mono, but you can buy a second unit to plug into the side of the first for stereo reproduction. They can be run from a Walkman-style CD or cassette player, or the output of your PDA or notebook.

So that's the technology, but how does the Olympia SoundBug sound? It's certainly not hi-fi; this is aimed at 10 to 15 year-olds and is sold as much on its novelty value as on its sound quality. The reproduction quality is very dependent on what you stick the device onto.

It sounds pretty good on glass, so a window is a good idea, except that since it vibrates the whole sheet, as much sound comes out of the other side of the pane as the SoundBug side. Good for annoying Saturday shoppers as you cruise down the high street, but you won't get the same effect as with a 500W boom box in the car boot. In fact, you won't get much bass at all. This is definitely a mid-range and treble frequency device.

£60 for a pair of speaker-makers like this may seem high, but they are incredibly versatile and will make you the envy of the playground - wherever you play.

The Olympia SoundBig is an ingenious device which turns any flat, non-porous surface into a loudspeaker. With careful choice of surface, you can get tolerably good sound out of a SoundBug (or two). They're well made, simplicity itself to set up and use and can make music just about anywhere that has windows or doors or tables or cupboards or ...