Question

which personal sound system would sound better, in terms of frequency response, one that extends up to 4 kHz, or one that extends to 9 kHz? and why?

Answer 1

from 3khz to 7khz, this range of frequency is better for our sense of brightness.it is good intelligibility.

This is the range of many speech consonants.

from 7khz to 14khz, this is range of treble. this range of frequency is difficult for the sense of our brightness. this range of frequency of sound is not good for human.

so, from above discussion, we see that 4khz is better than 9khz frequency of sound. because 4khz is more bright to sense compare to 9khz. 9khz carry too much energy that is not beneficiary for our sense. 9khz sound harsh and distracting.