How high frequency do you hear?

Human could hear sound from 20 Hz to 20,000 Hz, but if one ages, it become harder and harder to hear higher frequency. If you are a teenager, you would feel uncomfortable when you hear about 17,000-Hz sound. Well, some people utilizes that sound to keep young people away from a specific region.

Some medical researcher says, “Once you lost the ability to hear a high-frequency sound, it is impossible to get back.” However, vitamin C would prevent from such hearing loss.

Now, listen to the sound.