I have gotten this message a couple of times when I am playing through the game. It seems to happen whenever the bar at the bottom right of the screen fills up. I don’t have any idea what this meter does though. What am I meant to do when I see the message “you hear a strange sound coming from afar”?
You are correct in linking this to the meter at the bottom right of the screen. Spend crystals and it will fill pink, destroy the pink items for crystals and it will fill red. There is more about this in the games beginner guide. When you get the sound from afar message, head to a teleporting stone. You will see a new room has appeared on the map that you can teleport to.