Podcast THE TEACHER'S DEN

Our hearing ability ranges from 20 Hz up to 20,000 Hz. As we get older, the 20 kHz upper limit decreases. This phenomenon is medically known as presbycusis. Therefore, it is possible to generate high frequencies that are audible only to teenagers. Since these high pitched sounds are uncomfortable to withstand, they can be used -for example- to repel loitering teenagers in the street. If you hear this mosquito sound, it means you either are young or your ears are still in very good condition!