it might be your speakers. Speakers are't neutral, they are optimized for a specific frequency response. Which means that the loudness might be "dropping significantly" rather than you not being able to listen to a specific frequency. Use pro headphones to properly test your hearing :)

(that's also why expensive studio monitors cost so much - the "this song sounds good on any type of speakers, from in ear-headphones, to cheap car radio speakers, to pro headphones to on cheap television", master once listen/play everywhere, used to be a big problem in the audio world. (it might still be, but I left that world -- consider the cheap car radio speakers as the Internet Explorer 6 of the audio world and you get the idea!)

It’s not necessarily your ears. Could also be the frequency response of your speakers

This made me curious and I went and found https://www.szynalski.com/tone-generator/. (Can strongly recommend ignoring this site's volume control and using your own for the lower frequencies!) Playing around with briefly unmuting my audio output for short bursts, I found I couldn't go past 17kHz too. I did need to judiciously turn the volume up though.

We used something similar in school assemblys years ago, every student was able to hear it, the whole assembly errupted in chaos and none of the teachers were able to figure out what was happening. Good times.

Like short bursts over the PA? That's absolutely hilarious.

I'm 29, same with you.