The additional leverage of your leg must be nice, though. The automail, I mean. [He was pretty certain he'd go for the automail, even despite the risks. If Hiccup could manage and was doing well then he shouldn't back down.

But then the question caught him by surprise and he stopped short on his examination, both brows rising]

Well, a radio is a transmission device, picks up radio waves. They carry the sound so that you can hear me from a distance with the right receiver.

[Picks up his journal and points to it with a half-grin] Sort of like how the voice bit on your journal works, but instead of it being to one person, it's to whoever has your signal.