Um…...... yeah? It’s possible. It could totally be a way in which more aggravated dissociative states present themselves (as could all voices – like, gruff and deep and male on a teeny, high-pitched female). But, there’s also tons of other reasons among them for that, the biggest being that that’s just how some people talk, especially females. Or, simply being more socially conscious – I’m more likely to talk in a “child’s” voice, as it were, when I’m in a classroom setting and have to watch what I say than when I’m drunk in a bar and letting F bombs fly, or tired and kinda crabby. So, one of many, many reasons. And I would think if it was coming from an attempt to remain a mental child, the person would be more likely to use children’s various vernacular (eg baby talk, LOLspeak) than a soft voice, though they could easily combine the two.