NPCs:
NPC voice audio has it's own Audio Bank.
Personas are for NPCs. They don't only contain their voice information (which I presume filters through the Audio Bank by name, race and gender), but also their Homie icon and (according to persona.xtbl) what radio station they're listening to if they spawn in a vehicle (though I don't think this actually functions). For all I know, they may contain other information as well.
The voice audio might also be part of a "persona_situation". Eg; If an NPC with the "BM_COP" Persona (Black Male Cop) uses an Action Node (Eg: idle), they will only use voice lines labelled "BM_COP" which are included in the "voice - timeout" persona_situation (if there are any).
Another example I can think of is "IG_ep01_scene1.xtbl" (the mini-cutscene that plays when you save Pierce in the first Epilogue mission). The script has Pierce walk from the building and play the "voice - laugh" persona_situation. So each time this cutscene plays, the laughing audio would be different, because it's not directly calling for a voice line audio file, it's referencing a pool of laughing audios for the "SP_PIERCE" Persona (which npc_pierce uses) inside the "voice - laugh" persona_situation. If you were to simply replace Pierce in that cutscene, the replacement NPC should still laugh, but in their own voice (if they have laughing audio).
So the chain looks like this:
1. NPC
uses a...
2. Persona
which can encounter a...
3. Trigger (action_node, insults, compliments, etc.)
which triggers a...
4. persona_situation (a pool of voice lines)
which references...
5. Audio Banks
and then plays an audio file from the Audio Bank in-game.
Playa:
Playa has separate Audio Banks for each voice option. pcr01.lua (player creation) specifies these strings in the voice options menu:
MALE_WHITE
MALE_BLACK
MALE_LATINO
FEMALE_WHITE
FEMALE_BLACK
FEMALE_LATINO
These strings appear to be hard coded (or at least, I can't find them anywhere else). They are also difficult to mod in my experience. Maybe also due to the information being saved to the save file. (I tried to make a "Mute" voice option for
HS:Evo, but it didn't work).
The problem is trying to get the Playa to use a Persona instead of the Playa's voice options. Kanbei achieved this with CGallery files, but I suppose the next step would be finding and editing the same hex code in actual save files, possibly even then writing a script of some kind to do it through an in-game menu, which is beyond my capabilities.