Generally speaking, I live in hope that it is thoughts I am verbalizing.
But what you describe is not unusual for extroverts. Some seem to need to work out their thoughts by speaking them aloud. I have known one or two whose procedure seemed to be to say something and hope that it made sense.
Are Americans in general more extroverted? I don't know, having lived mostly among native Americans, with a sprinkling of immigrants, all my life. I will say that there are large regional differences within the US. A saleswoman at a dealership in central Pennsylvania once unnerved me by saying nothing for a minute or two: in the Washington, DC, metropolitan area, auto sales personnel do not like dead air.