High Quality Content by WIKIPEDIA articles! The Mosquito or Mosquito alarm (marketed as the Beethoven in France, the Swiss-Mosquito in Switzerland and SonicScreen in the US and Canada) is an electronic device, used to deter loitering by young people, which emits a sound with a very high frequency. The newest version of the device, launched late in 2008, has two frequency settings, one of approximately 17.4 kHz that can generally be heard only by young people, and another at 8 kHz that can be heard by most people. The maximum potential output sound pressure level is stated by the manufacturer to be 108 decibels (dB). The sound can typically only be heard by people below 25 years of age, as the ability to hear high frequencies deteriorates in humans with age (a phenomenon known as presbycusis).