PHILADELPHIA (WPVI) -- Some young people are hearing a high pitched frequency at parks around the city.According to Philadelphia's Parks and Recreation department, a device called "The Mosquito" has been popping up at parks around the city since 2014.The device goes off from 10 p.m. to 6 a.m., blaring a high pitched sound that anyone over the age of 25 should not be able to hear.It's currently installed at 31 city-run locations in Philadelphia. The devices are meant to prevent vandalism and loitering by teens and young people at these public parks."It sounds like a high pitched ringing noise," said Kate Sexton, from Fishtown."It's annoying, it kind of makes your ears hurt a little," said Analiese Gale, from Ardmore.These devices are installed at the request of the community, a district council member, or in one case the police.Some of the devices also have cameras installed into them to catch vandalism or groups gathering late at night causing a disturbance, according to the city's Parks and Recreation Department. CCTV security cameras are currently installed at more than 60 percent of Parks and Rec facilities, with plans for cameras to be installed across all sites with this system.The city's Parks and Rec Department explained their reasoning for the devices."Parks and Rec takes holistic, community-focused approach to maintaining safe and welcoming environments for staff and residents. Working in partnership with community members, advisory councils, friend groups, and local law enforcement, we take an individual approach to safety each site based on its needs," said Maita Soukup, a spokesperson for the Parks and Rec department.The devices were installed in Washington D.C., but have seen been removed for alleged age discrimination complaints. They have also been banned in some parts of Europe as they may violate the rights of children.Some young people Action News spoke with said they didn't think it's fair that older people couldn't hear the sound."I feel like there's a lot of older people that would be here at night, and I think they should be targeted as well because I see a lot of older people causing trouble in parks at night," said Sexton.Parks and Rec said, in general, they've seen a reduction in vandalism at these sites. The devices cost around $5,000 for the equipment and installation. These devices help maintain a 10 p.m. curfew that exists across the Parks and Recreation system. They are meant to keep teenagers from congregating in parks after hours when parks are closed.Cione Playground 2600 ARAMINGO AVE 19125Cohocksink Recreation Center 2901 CEDAR ST 19134Ford Recreation Center 609-39 SNYDER AVE 19148Markward Playground 400-16 S TANEY ST 19103Kendrick Recreation Center 5822-24 RIDGE AVE 19128Rose Playground 7401 LANSDOWNE AVE 19151East Poplar Playground 800 N 08TH ST 19123Fishtown Playground 1202-32 E MONTGOMERY AVE 19125Hancock Playground 147 MASTER ST 1912212th & Cambria Playground 1149 W CAMBRIA ST 19133American Legion Playground 6201 TORRESDALE AVE 19135Bridesburg Recreation Center 4625 RICHMOND ST 19137Piccoli Playground 1501 E BRISTOL ST 19124Waterloo Playground 2502-12 N HOWARD ST 19133Belfield Recreation Center 2109 W CHEW AVE 19138Water Tower Recreation Center 209-99 E HARTWELL LA 19118Boyle Recreation Center 13024 STEVENS RD 19116Chalfont Playground 4336 DEERPATH LA 19154Fitzpatrick Playground 3500 ACADEMY RD 19154Fox Chase Playground 601 BORBECK AVE 19111Junod Park 3102 MECHANICSVILLE RD 19154Lack man Playground 800 BARTLETT ST 19115Mitchell Playground 3694 CHESTERFIELD RD 19114Palmer Playground 11701 THORNTON RD 19154Picariello Playground 3325 RED LION RD 19154Lower Mayfair Playground 3001 ROBBINS ST 19149Pleasant Playground 6750 BOYER ST 19119Dorsey Playground and OL 6501 HEGERMAN ST 19135Emanuel Recreation Center 8500 PICKERING AVE 19150Glavin Playground 3267-81 ALMOND ST 19134Barrett Playground 8th & Duncannon