There is a certain tone with which I speak when I am speaking to no one in particular.It is one I do not think about; the words simply come to me, so they are the ones I use. But when I talk to other people, it changes.
I wouldn't say that I put on a mask or anything like that. In reality, I tend to match people's energy. If they're hyper and wacky, I'll be hyper and wacky. If they're being philosophical, I'll do the same. And if they're boring, I'll go ahead and match that, too.
What I find fascinating is how my close friends have their own styles, which I have really honed in on and developed my own version of. But that means that I have a version of speech that is unique to all of the close friends in my life. What is even more fascinating to me is that I can instantly switch between them.
All it takes is one sentence on their part and I'm in the mindset. Sometimes it doesn't even take that much. Sometimes just seeing their face or their screen name will orient me. I know what words I'll like to use, what catchphrases get the laughs, and even how to punctuate and capitalize (come people need all caps and three exclamation marks, and some need zero of both)
Ironically, I find dialogue one of my weaker skills. Don't get me wrong; I can make compelling speeches and conversations. The problem is that they all sound like me.
One of the exercises I am working on is being able to create a speech pattern for each of the characters that will talk. It is a serious task, but I think it will be worth it if I can get my characters to sound like people and not like author avatars.