Can you hear this sound? Probably not if you’re over 20.
Carl Fredericksen for hearing loss
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I came across this interesting phenomenon the other day. It is a sound that only people under 20 can hear. The sound is a sine wave at 18,000 Hz. Dog whistles produce sounds at about 16,000-22,000 Hz.
Scroll down to the bottom to play the tone.
I downloaded the sound and played it very loud on my Mac and I can just barely make out a slight whine (I’m quite old, according to my son). My kids on the other hand heard it quite loudly and it hurt the oldest’s ears. (He’s 17, so he’s got a few more years to hear it).
Supposedly, some teens use this as a ring tone on their cell phones because they can use it in class and their teachers can’t heat it. Not sure why they wouldn’t just use "vibrate".
It has also been broadcast in areas that authorities don’t want teens to congregate because the sound is quite annoying to them, but adults can’t hear it.
Damaged hairs in the inner ear.
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As you age, you lose more and more of the fine hairs in your inner ear. Higher frequencies are the first casualty. As you experience true hearing loss, usually you can only hear very low frequencies. Exposure to loud sounds can hasten this process. Obviously, music played loud on an iPod or loud video games that are quite commoon with "kids these days" are taking thier toll on their generation’s hearing.
As I understand it, there are also some changes in the way frequencies are transmitted to the brain which occur naturally. It is this phenomenon that accounts for the way this tone works.
I also came across some interesting Audio Illusions (which include this phenomenon). Check them out here.
Play the sound here:
Oddly enough my grandma would find your site very interesting