That's why the headphones I use range up to just 20kHz, instead of 30kHz, or the 100kHz that the better headphones can reach. Humans just can't hear that high, but the range of those headphones also means they have better response to frequencies near the upper extent of human hearing. Middle-aged humans usually will lose the upper range between 14kHz and 20kHz, with the elderly sometimes losing a great deal more. The most important range for humans is between 85Hz and 255Hz, which is the range of human speech (men ranging in the lower 100Hz, and women in the upper). Bass response is usually weakest in headphones because of the relatively narrow cone size, and short coil lengths, but you do not need a lot of bass anyway, really. At least, not right up next to your ear you don't.