You have any objective evidence you can hear above 20k Hz?
It’s not just the cutoff in frequency, it also has to do with the digital sampling rate. The higher the frequency of the waveform, the less accurate the sample will be. With the CD sample rate, you start to lose some of the quality of the reproduction of the analog signal long before 20Khz
I have noticed that I can hear very high frequencies, but it’s the low frequencies that matter in this case. Humans can’t truly hear low frequencies, but can feel them, and that adds to the “depth” and resonance of the sound. Low frequencies are often part of the way we distinguish one sound from another, and can help with the differentiation of various instruments i.e. a pedal tone on an organ (a real, wind-driven one) sounds different from a low bass viol string or a tuba.