How you measure your hearing? Are we talking about the measurable or subjective definition?
I do with simple youtube 20-20000 test tone and look at the digit when it goes totally silent. If you hear sine wave of 15kHz+ this is very very good. Most of my age friends hear even a bit less than me, that is LESS than 14kHz and all of us are 38-45smth.
Testing your ears with a YouTube video is not ideal because you're also testing the performance of the lossy audio codec. That will be either AAC or Opus depending on your listening device, and the bit rate depends on the resolution at which you watch the video. Using a lossless source like a test CD is better in terms of audio, but those don't have the handy on-screen display of the current frequency.
You are also testing the performance of your computer's DAC. But if you are here you already know that and you are using some sort of quality DAC, not a bottom of the barrel one on a cheap motherboard.