The high end of the sound spectrum is what starts to go first as we get older and based on how much exposure you've had with loud noise or music will contribute to your hearing loss sooner or later. Many will experience not understanding people when they speak, that's because the high end of the sound spectrum is what determines clarity of speech. Having trouble understanding children or women or not hearing the cymbal of a drum set is all part of that hearing loss.
So, it's not actually not hearing people speak, which you do hear, it's not understand them because of the high end loss.