"their" > "there", "convolong" > "convolog"
Damn, I can't write.
It would have to be pretty finetuned, and not simply like the current AoE for floating text is, as you can easily get flooded by them, from far away.
Definitely the most worrisome spot I think; that market...
Audio scaling to range is already in the game. You can hear it all the time with other sound effects. Listen for it the next time you approach a waterfall or two NPCs sparring in town. There isn't anything difficult about applying it to voiceovers.
Right now I can see NPC text spam too far away. I can, for example, hear the two guards patrolling in the main city from the docks. I can hear Ishamashell from the initial starting location after character creation. I can hear the two guards arguing about the charmed female orc from out on the beach where the first orc attack occurs. By "hear", of course, I mean my chat log is filled with text spam.
If they don't fix that, and then they make the additional mistake of setting voice to the same range, then yes.. an existing problem will only be made worse. Both voice audio and text need to be tuned to the appropriate range.