Introverts live in two worlds.
The first world is the endless cacophony around them. Extroverts want to speak, to tell you about the petty little slights of their days, their loves and losses, the football scores, scoring in general, fears, and family problems. Actually, that's more of a romantic lie than truth. Most talk is more chat than conversation: news updates, gossip, slander, and internalized insults that need reception. In this world, the introvert persists, listening and wondering why every thought necessarily must become a word, why the world has to be filled with so much sound when silence is so comparatively majestic.
The second world is internal; it is the world I live in my mind--a self within the listening self. So often, I'm listening but thinking elsewhere (yes, that makes me a terrible person). My thoughts are words that never gain voice. Sometimes I'm listening, but thinking: I wonder if they know how long they've been speaking to me without my reply? Sometimes when I have a thought, have weighed it properly and found it sound and fit, and I prepare to speak...I find the conversation has veered so far asunder that my input seems ridiculous. The second world is every word I've thought and decided not to speak.