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Now test your own hearing!
8 kHz
Everyone should hear this.
12 kHz
On average, this should be heard by people under 50 years old.
15 kHz
On average, this should be heard by people under 30 years old.
17 kHz
On average, this should be heard by everyone under 18 years old.
20 kHz
This is the highest frequency humanly possible to hear.