Well... I was
going to say that according to datamined info each villager has a set "low", "high", or "normal" version of their personality type's voice and you look on
this spreadsheet under the column labeled "_aa4403ea voice" you can see what each of them has, but? I must be wrong here somewhere because Colton and Marshal's are both labeled normal and if Marshal obviously has a higher voice than Colton, then I can't be entirely correct... sorry I couldn't be of more help but now I'm curious about this too!