The AI Voice level of persona components is too low, and it can’t be tweaked from anywhere. If you compare it to the default dB of other apps, its 4 times lower in volume than what it should be (if it was a wave file inside UEFN, I d add it inside a cue and set a modulator with volume 4, when 1 is default).
I assume this is not an issue of the device, but a massive issue that UEFN has since launch where its default volume mixer is set to be 4 times lower than what it should be, and Epic cant fix now because it will make all old games really loud (we had to compensate through cues or setting volume inside sequences). However, there is no setting that we can tweak for the persona device, making all character talk really low in volume and the only workaround is to make the entire game almost silent so you can hear them.