Although there's also a difference between being able to hear a single tone, and being able to reliably perceive a difference in some more complex bit of noise.
Testing with https://www.audiocheck.net/blindtests_frequency.php, my hearing limit in the white noise case for example is at least 1 to 2 kHz lower than my hearing limit for a single frequency sinus tone.
Oh absolutely, hence the stressed out words in cursive. It isn't going to make any meaningful difference even for a 10yo with perfect hearing - for listening, 44100Hz sample rate is more than enough, and 48000Hz provides large enough headroom to already make any semi-reasonable "audiophile" sleep calm.
I used to be able to locate the computer section of WH Smiths or John Menzies in the 1980s and go and play on the ZX Spectrums and Commodore 64s (and other oddities - the one in Arbroath had a couple of Memotech MTX512s!) by hearing the 15kHz scan line whistle from the CRT tellies they used for displays.
I know that when I was about 10yo, I could hear a tiny suggestion of something audible when I tested my hearing at around 23-24kHz. I guess that if you had some really loud content around these frequencies and had equipment that could reproduce it perfectly, it would be not impossible for it to influence my listening experience those many years ago :)