The highest frequency that the human ear is capable of perceiving is 20 KHz, although this frequency decreases with age. The speakers of mobile devices do not usually emit sound above 20 KHz, so this app is limited to 20 KHz. Most adults cannot hear above 15 KHz. Do not use with headphones. In case of discomfort, dizziness and other symptoms stop use immediately! Do not use this application as a weapon against dangerous animals. The application is used at your own risk. The developer bears