If I'm in a one-on-one convo with an extrovert, especially another ENFP, I get super loud. The more excited I get, the louder I get and it seems they bring out my energy by verbalizing how they relate to what I'm saying. Or maybe it's me trying to control the conversation before they change it to how my relationship relates to them. Either way, yes, I am louder than the average person at times.
I recall the first day at my current job; I was talking with an EXFX and a lady across the room was on the phone and actually screamed for me to be quiet. What an embarassing welcome. It wasn't until then that I had realized how loud we were getting. Now I try to be more aware of it at certain locations where it would be appropriate, i.e. an office environment.
What we think, or what we know, or what we believe is, in the end, of little consequence. The only consequence is what we do.