When the personal stereo first hit the ears of the nation in the early Eighties, all eyes were on the diminutive tape-player. Inevitably, miniaturisation soon infected the headphones too, and ever tinier speakers were wrapped around ear drums.

Then hi-fi buffs saw to it that the enormous headphones ("cans") on which your mum demanded that your dad listened to Gerry Rafferty (ouch!) were altogether cooler. Thus was created the air-traffic-controller look. Take a look on bus or train and there'll be a "youth" (it's invariably a bloke) solemnly nodding his head to muffled beats with what looks like half a football strapped to each ear. Part of this look works on the iceberg principle - nine-tenths of the technology is invisible, and we are meant to assume that the pounds 100 headphones are just the start of the owner's pocketful of hi-fi dynamite. But you can bet your favourite tape that the state- of-the-art cans are hooked up to a straight-out-of-the-ark personal stereo.