I dont know. I DM dungeons and dragons. I did this back in the 1980s and I started again a few years ago. I've never been able to do voice acting for NPCs. I now realize it is because I dont have a minds ear and would have a different voice the next time the NPC had to talk. If I had known this about myself was due to aphantasia I may never have been confident enough to be a DM. Brand new thought: I never considered my stutter in regards to DMing. I rarely stutter while playing. Otherwise as a DM I feel I am very good. I am a quick thinker and when I am free thinking and speaking I dont really stutter. For me it was mainly reading or speaking a memorized speach.