Noise is the principal product and validating sign of civilisation. But now it is being turned into a shield against the excesses of contemporary civilisation. We report a remarkable crescendo in the sales of mosquito noise. The largest and most celebrated stores, banks, local authorities and railway companies are investing in this ultrasonic teenage youth deterrent.

The “teen tormentor” or the “teenage buzz” emits a high-frequency shriek that is intolerable to the young, but inaudible to anyone over the age of 25. For adults develop a selective deafness at the high frequencies as they grow older. But mosquito noise turns off unwanted and antisocial young from places where they congregate, faster even than the music of Mozart. It is a deterrent and an aural aegis. It clears car parks, shopping malls, churchyards and pavements of troublesome, threatening, congregating or even simply superfluous teenagers, leaving the public space free for grown-ups to shop.

There is precedent for thinking of noise as a turn-off as well as a sign of humanity. Pascal was wrong when he wrote that he was terrified by the eternal silence of infinite space. We now know that it is noisy up there, most of the noise being man-made. Dante’s Inferno is hellish hubbub. To have invented clever acoustics that can be heard by bugs but not by beetles is as remarkable as the alchemist’s stone that turneth all to gold.

Yet like that magic stone, mosquito noise may also have flaws. For one thing, these allegedly turbulent young may be too wrapped up in hoods, their iPods and themselves to notice. And for another, the future, as usual, belongs to the young. They are using mosquito buzz as a ring tone on their mobile phones, so that they can be covertly telephoned in places such as lecture halls. Did you hear that noise?