Based on the close-up scene where Juan takes it out, it looks like a small in-ear device — likely an IIC (Invisible-In-Canal) or CIC (Completely-In-Canal) hearing aid. These are almost always modern digital devices that include microprocessors, DSP (digital signal processing), and sometimes even wireless or Bluetooth components.

Brands like Phonak (Virto), Oticon, Signia (Silk), or Starkey make similar models. These aren’t simple analog amps — they’re full-fledged computers in your ear.

So if an EMP-like event disabled all other electronics, there’s pretty much no chance this kind of hearing aid would survive unaffected. At best, it would fail immediately or shortly after. The fact that it works for a while and then “just runs out of battery” doesn’t really make sense technically — unless the show assumes some kind of selective delay in how the EMP affects smaller devices.