General Hux is deaf. Up to you how it happened maybe he was born deaf or maybe something happened to him as a child. Either way the Commandant couldn't be seen having a child with such a weakness. Luckily Hux was able to get implants as a child. He rarely thinks about the fact that he can't hear without them. Of course then they get damaged, maybe on a mission gone wrong or when Hux is captured or maybe they just short out on the bridge. Cue Hux trying to hide it and Kylo who was previously unaware realizing Hux is still the same badass and nothing has changed.

+ The boys trying to hide it from the rest of the crew
+ Angry force conversations
+ Kylo and/or Hux signing