So in this way, perhaps it's like a morse code to them. They can "talk" by shifting colors and detecting changes in the visual wavelengths... similar to how we

So in this way, perhaps it's like a morse code to them. They can "talk" by shifting colors and detecting changes in the visual wavelengths... similar to how we vibrate our vocal cords at different frequencies to form words, and detect the changes in pitch with our ear drum. Now that I've written it out, it seems silly to put "talk" in quotes. They are definitely talking. We just don't know the language. This makes me want to watch Arrival again :)