For some reason most hearing tests cut off at 8 KHz. I know someone who passed a hearing test and yet when I tested her hearing with higher frequencies, she couldn't hear anything above 9 KHz. It seems to me that the standard hearing test is probably not finding a lot of people who already have some hearing damage.
Generally speaking, voice communications has very little to do with frequencies above 8 kHz. The same is true below around 300 Hz. The critical range to understand speech well is around 300 Hz to 3400 Hz. So that's what they test...