I wouldn't put much faith into this test. Its results are highly dependent on your audio equipment's ability to reproduce high frequency, and the typical computer-based audio gear is woefully lacking.
I ran the test twice: first with speakers, second with a headset. In the first test, my hearing was equivalent to an 82 year old, in the second it was equivalent to an 89 year old. In the first test I stopped hearing the tone when the frequency got up to 5.6 kHz.
I am 77. I know that I don't hear as well as when I was 20; at that age the horizon sweep oscillator on a TV set used to drive me nuts - its frequency was 15.5 kHz. Back then I had been tested professionally and could hear up to 18 kHz. It has been years since I heard ANY TV's oscillator.
So this is fun, but it is entertainment *only*!
Abe