"High-quality speech systems need to cover the frequency range of about 80 Hz (for especially deep male voices) to about 10 kHz (for best reproduction of consonants, which are crucial to intelligibility). Response below 80 Hz must be eliminated to the extent possible: not only do these frequencies fall below the range of the speech signal, but also they will cause particularly destructive masking at high sound levels."
So, 80 to 10kHz is necessary, OK. However, eliminating response outside that range is either irrelevant (if there is no signal content outside the range) or a big mistake resulting in loss of program material (if there is signal content outside the range). So, if it is the latter, one may achieve some advantage in voice intelligibility but at the cost of loss of other content. IMHO, a bad trade-off.
Kal