From this week's Earth Beat: a new weapon to fight unwanted noise. More noise. Silent sound is rapidly becoming the way for getting noisy teenagers to leave an area. The Mosquito is a piece of equipment used to disperse groups of young people in public spaces.

It works by emitting a peep at such a high frequency that only people under the age of 25 can hear it. The idea is that the tone’s so annoying they are forced to move somewhere else.

Earth Beat’s Marijke Peters – who’s well over 25 – went on a late night trip to one of Amsterdam’s squares to find out more.

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