Though Fallout 4 will let you fiddle with all manner of aspects of your character's visage, creating your very own post-apocalyptic mumsona or dadatar, the words coming out their mouths always sound the same. That can change with the Player Voice Frequency Slider mod by "CDante", which adds options to fiddle with the pitch of your character's avatar and make them sound different. Obviously it's not as good as having lines recorded with wholly different voices--such as the delightful mockney accent option of Saints Row--but it seems to allow some decent variety in personality. It's pretty good too; listen to this teenager.
That's not bad for simple frequency-fuddling! Obviously the voices get sillier as you move to the extremes, up into the realms of The Chipmunks or down to yer da after his traditional Christmas morning pint of sherry. But with moderation, you'll get to personalise your post-apocalpeople a little more.
The mod comes with four presets--Teenager, Young Adult, Heavy Smoker, and Very Deep--but you can also adjust it yourself in little steps.
Download CDante's Player Voice Frequency Slider mod from Nexus Mods. It needs the Fallout 4 Script Extender to run, and you might also want to use the Mod Configuration Menu for a simpler and snazzier way to tweak the voice.
God, I do miss that mockney.