I like to think conversation is the old word for conversion. This allows much better description of both words. Conversion seems to be something involving two things with one changing into the other. But conversation involves much more changes as just one, thought to motion to sound, muscles to speech to ear to nerve to thought and back to words again. A single conversation involves changing something lots of times. A conversion is nothing less but we ignore the sub products. In that same way conversion describes the phenomenon called conversation. All to often we tend to forget to focus on the product of our chat.
Ironically we all know a story is never preservated in conversation.