I was thinking as I was responding to someone's comment on hearing loss, since we have a common problem with it as I have a hearing loss issues along with severe tinnitus. The higher frequencies are very difficult to hear and it would be nice to be able to alter/adjust the range of sound frequencies (to a certain extent). We can already adjust back ground music, NPC voices and some in game sounds which have helped to a small degree but to be able to adjust the frequency range would be ideal.
I use the in game closed caption which helps with in game dialogue but there's nothing for person to person communication. Being able to adjust frequencies when speaking to people would be very helpful.
Hearing loss is different from person to person, so by adjusting to a specific range of sound frequencies, each person could customize their sound preference to their account.
Just a thought ~ Cheers