I think this may be connected to the "listening" gift that Nardi notes in Fi-dom.
I really, really listen when other people speak. Sure, like any human there are times I'm distracted, daydreaming, or focusing on my own thoughts, but it's not hard for me to become engrossed by a speaker, whether one-on-one or in a crowd. I'm sure I LOOK focused & maybe a tad hypnotized (although I'm not really influenced that easily), and this sort of sucks the person speaking in as much as I've been pulled in to them. In social situations, this can be creepy to people though (I won't elaborate on that here).
When it's a crowd, I think the speaker sees you're one of the people intently listening, and then it's natural for them to start focusing on you (and speakers often, whether naturally or because it's recommended, choose a face or a few to focus on as a technique). So then, as the one listening, you notice they're looking at you a lot. There's eye contact.
I think it's an interesting mix to listen intently & also resist outside influence on your feelings. Especially as a child, I was like a sponge or a spy - I soaked up a lot, I heard a lot, I observed a lot.... but it didn't directly affect me. This is probably Pe to some degree to & why Fi valuations aren't formed in a bubble. You note things, and Fi gives dignity to others by valuing them enough to listen, but it's your own internal scale that decides the weight of what's being heard. So it's like, someone says, "XYZ is important!" and what I take home is "XYZ" and decide what meaning it has. I notice many other people (usually Je types) will hear the same thing, but either reject or accept the importance of XYZ as a whole, not assigning it their own meaning. Since I'm not focused on rejecting/accepting when listening, I',m just, well, listening & this becomes apparent & sometimes attractive to the speaker.