I’m not sure about his case, but that does look like a hearing aid or some other “stuffed in” device. I have several friends who have SOF experience; at minimum they tend to listen to music/TV at high volume and one often needs to speak more loudly with them… they’ve been around things that go “bang” a lot.
OTOH, they’re often tracking a bunch of different things at once; ironically, this means they’re both keenly observant and constantly distracted. I will not admit that I use this to my advantage while playing cards…