How old are your ears?
If you can hear 5khz to 8khz you are both alive and not hearing impaired.
12 khz- under the age of 50.
15 khz -under the age of 40.
16 khz -under the age of 30.
17 -18 khz -under the age of 24.
19khz - under the age of 20.
20 khz- This is a mosquito noise. You should only be able to hear it if you are under the age of 18.
The inner ear does not have the capacity to regenerate. In your ear there are thousands of tiny nerve cells called hair cells. These are responsible for picking up different frequencies and send the signal to the brain where it's processed, but as you age the continued exposure to noise and loud sounds can break bend and destroy these cells. It turns out that the hairs tuned to high pitches are the first to encouter sound waves. As a result, they experience more stress and tend to degenerate earlier. Which is why the older you are, the harder it is to hear high pitches.