> most people are hearing mostly between 2000 to 5000Hz

That's pretty misleading, we tend to have excellent hearing anywhere in the 100 hz - 6000 hz range. Much of music and all fundamental frequencies produced by the human voice (except people with very rare whistle register abilities) is below 2000 hz. We're most sensitive to the range you're talking about because it's the most useful for discriminating between different sounds, but still only slightly more sensitive to that range than to lower frequencies.