There are so many ways to communicate. Some, like sign language, don't even require sound, or use little of it. Many of the optional means for communicating have names of their own. Likely, you've come across these speech forms before. Which of them have you used? How many of them do you speak?
I'd say I speak the English language with a Midwestern dialect. I use legal jargon from time to time, as well as a "faith based" lingo when among particular friends, and sometimes, I use slang. Finally, my writing encompasses specialized terms, which might be identified as the use of an argot (although not for an underworld group or group of thieves) for specific people in my stories.
How about you? What do you speak?