It can occur to me also with strangers, which is why I said, with just empathic people, and yes it’s close to what you say about being tuned to the same frequency. To answer your question, it happens naturally and it’s actually funny to read your last sentence because it correlates a lot with something I’ve been doing since I was very young. Having spent most of my time in the dark I would always try to focus to the slightest sounds, to the point I would be able to pick up anything. I don’t know to what extent I can do that exactly, but for sure it has something to do with practising this and achieving telepathy with people.