Some kind of code

A comic: a little girl and a funny-looking alien are sitting on a magical floating island. Below the image is the following text:  "You have no telepathy at all? Not even at close range? I don't get it. How could your species develop technology and written language if you can't even talk to each-other?"  "We can talk to each-other, just not mind-to-mind. We talk with our voices, with our mouths. You know, this hole in my face? It's not just for putting food in, it has another function too. See what I'm doing right now? This is how we talk."  "You keep opening and shutting your mouth. Is it some sort of code?"  "It's not really about the mouth itself, it's about the voice. The sound that comes out."  "Sound? I'm still not following you."  "Sound is... it's hard to explain... it's a compression wave in the atmosphere. We generate them with... with a thing inside the throat, and it comes out of the mouth, and we can detect the sounds that other people made using a... an eardrum, a thing inside our head that detects vibrations."  "Huh. Neat!"

The floating island is based on an image from Glitch.