TOKYO (Reuters Life!) - A Tokyo park has started playing a high-pitched tone at night that only young people can hear to help drive away teenagers who keep vandalizing the toilets and other facilities.

"We were having trouble improving the situation and trying to decide what to do, when we found out about The Mosquito and decided to give it a try," said Haruyuki Masuda, an official in charge of parks in Tokyo's Adachi district.

"The Mosquito" is a device that emits a high-frequency tone that is unbearable to those who can hear it, Masuda said.

The local authorities decided to act after young people hanging out in the district's Kitashikahama Park inflicted damage amounting to around 700,000 yen ($7,400) there last year.

"We could not do anything about it from just patrolling," Masuda said.

People's ability to hear high frequencies falls as they age. The device produces a high-pitch tone of around 17 kilohertz, which teens can hear but older people cannot.

While such devices are used at some convenience stores in Japan also troubled by teens, Masuda said district officials were hesitant at first.

"We were a little worried about whether the local government should be using such a device to exclude certain people, even if these are young people that are causing problems," Masuda said.

"But we have been unable to resolve the issue and many people said we should try it," he said, adding that the device would be tested at the park from 11:00 p.m. to 4:00 a.m. each night until March 2010.

(Reporting by Yoko Kubota, editing by Miral Fahmy)