*kicks the door down* All I had to hear was Au Ra, horns, and ear, I feel so strongly about this topic I can't even
Starting this with the reminder that this is a fictional world with fictional lore and people should absolutely engage with the content the way they want and interpret or reject canon as much as they want for their blorbos. Be cringe, be wild, be free.
NOW ON THAT NOTE HERE'S MY SLIGHTLY RELATED SOAPBOX OF WHAT I DO FOR MY LOVELY AU RA BOY:
Canonically, horns = ear but ears have more moving parts than just "ear" generally encompasses. I believe that the horns act the same way as a pinna or shell of an ear. It's just the outside, gathering vibrations and sounds and directing them both with the hollow interior (I'll get to this) and with the shape of the horn. There is NO WAY the ENTIRE hearing organ is the horn. If this were the case then every Xaela ever in every fight ever would be targeting horns cause heavy metal clanging against that would be crippling. Our ears control balance as well as sound processing, a smack with a shield to a horn would completely drop someone. I have a hard time believing a series of Tribes that frequently clash, whose entire ruling body is decided by the annual, violent capture the flag, would unanimously agree that "horns are off limits" and go into battle with the most obvious weak spot ever.
I DO believe that the horns are instead less about the interpretation of sounds and act more like an additional sense of spatial awareness. I believe Au Ra have a hearing canal at the base of the ear (this is where they reach when interacting with a link pearl) the same way we as human have a little hole in our head right next to the shell of the ear. They likely "hear" things the same way we as people do which is why they have vocal languages the same as us but in addition probably have a firmer grasp of more sensitive vibrations. The inside of the horn can't be entirely hollow or it's going to be an echo chamber in there and more likely has a sort of mesh like the "hollow" of bird bones to trap vibrations and "focus" them into understanding information about the environment. I think Au Ra as a result are extremely difficult to sneak up on and have incredible battle awareness, which tracks with their cultural predisposition to combat when protecting flocks, defending territory, and other disputes. Never mind the value such an awareness would have dodging predators themselves as Xaela in particular are preyed upon by Matanga, Baras, and other predators.
The same way the shell of our ear has feeling, I think their horns do too. Being of a thicker and stronger material they may not be as sensitive but I feel like that boils down to the individual. I know people who have extremely sensitive ears and people with a dozen piercings who didn't feel a thing getting them. The thickness of the horn, the scale pattern, and other factors could weigh into the sensitivity. My boys horns are not particularly sensitive. He has used his horns to block weapons before (it wasn't pleasant and he was a little dazed) but he has enough feeling to enjoy when his partners rub his horns. The sound of gentle rubbing and the feeling of it is soothing for him.
The way we casually use the term "ear" in RP/writing/etc, generally refers to just the outside shell, we don't picture the ENTIRE organ when we hear the word "ear" so I think in that sense, yeah horn = ear and for RP purposes that makes sense. I'm with the person who said "to" the horn sounds more natural than "in" the horn when whispering.
TL;DR - I just wanted a flimsy excuse to publicly talk about this - Horns are just the outside of the ear, there's an aural canal
