Download Wave Here: 18000Hz Sinewave (under 20s)
Try hearing this sound. It is called “under 20s” sound as the elder’s can’t perceive it. It is a sine wave at 18,000 Hz (by comparison, a dog whistle sounds at 16,000 – 22,000 HZ – meaning a dog can hear this sound as well). This sound is used by some teenagers as a ring tone on their cellphone so that only they (and others of their age group ofcourse) can tell when the phone is ringing. It is also occasionally used in England to play very loud in areas that authorities don’t want teens to congregate in, as the noise annoys them.
The inner ear of the humans have a functional design to hear sounds in a range of a frequency. Hearing is not merely a function of ears but the oscillation amplitude is conducted to the brain. As people get older they lose the ability to hear higher pitched sounds. As people get older they lose the ability to hear higher pitched sounds – that is the reason that only young people can hear this sound – it is too high for most people over the age of 20.