The Mosquito is an electronic device that emits a high-pitched pulsing tone, in the region of 16 to 18.5 kHz, intended to discourage young people from gathering outside shops, schools and stations. Because sensitivity to very high frequencies declines with age, the sound is usually audible only to children, teenagers and people in their early twenties. It was invented in Britain by Howard Stapleton, a former British Aerospace engineer, and went on sale in January 2006, after which it was installed at thousands of British sites.
The device became a test case for the ethics of sound in public space. Critics argued that it affects every young person in range, babies included, whatever their behaviour, and on 25 June 2010 the Parliamentary Assembly of the Council of Europe adopted a recommendation calling for its use in public places targeting young people to be banned and its sale prohibited. In a culture that usually treats a sustained tone as something offered for listening, the Mosquito is an instance of one used to keep a particular group away.