Memeage
You are in your twenties
You can still hear reasonably well and you can play this without my old fart colleagues hearing it which makes you feel kinda good.
The highest pitched ultrasonic mosquito ringtone that I can hear is 15.8kHzFind out which ultrasonic ringtones you can hear!
Mind you, I can almost barely hear 16.7kHz but that is almost exactly the same tone as the ringing in my ears. I doubt I would hear it randomly, but I can tell the difference between it playing and it stopping when I'm listening for it. And sadly, I'm not joking. Too much loud music in my youth, and I wasn't even a concert goer, I can solidly blame headphones. :P