Why do some walls in my house vibrate?

I don't know if this is the right place to ask this. I pressed my hand against a wall in my room, and could feel it almost vibrating, or fizzing like it was carbonated. I've been checking around the house, and it's not every wall, just some of them. I looked up what that could be, google said airducts, but I don't think my house has any,it's really old. I checked my fish's bowl on a whim, and it was vibrating very slightly too. Is this an earthquake?