I remember when I was a kid, I made little films in my head and then I talked as if I were a character of the film. I did it with cartoons, for example I was obsessed with the Lion King, and so I talked loudly as if I were one of the characters in the cartoon. For me it was a way of playing. Then I remember when I was a kid I talked to myself as if there were others listening, I knew I was alone, but it was a way to express loudly my thoughts, I think it was a compensation because I was very shy and never talked to others.
Now I always talk to myself, if I'm alone I make conversations loudly, directed only to myself. And sometimes I talk as if there is another character with me, "living" in my head, I know that sounds crazy...but it's like I made this boy figure in my mind, (I see it as an archetype, it's like a male figure of me it that's make sense), I gave "him" a name. And so, this "character" sometimes talks and says very positive things, about myself, giving me insights of situations I'm experiencing, in a positive way. Of course, I know that this characher doesn't really exist, it's a part of me, but I find it helpful to talk to "him" because this figure says very positive things and helps me.
So I think if these conversations with yourself doesn't trouble you, and maybe they bring up something good and positive, I don't see problems. Maybe talking loudly could be a way to compensate, for example, if you usally don't talk much with people and are an introvert, it can be a way to recreate conversations that your mind needs.