Sounds with frequencies above the highest note on the piano keyboard, around 6000 Hz and more, sound like a high-pitched whistling to most people. Above 20,000 Hz most humans don’t hear a thing, and by the age of sixty, most adults can’t hear much above 15,000 Hz or so due to a stiffening of the hair cells in the inner ear. So when we talk about the range of musical notes, or that restricted part of the piano keyboard that conveys the strongest sense of pitch, we are talking about roughly three quarters of the notes on the piano keyboard, between about 55 Hz and 2000 Hz.
