Do these tend to refer to audio players in particular, or to any ear covering? I'm curious (1) whether that applies to balaclavas for warmth in the winter and

Do these tend to refer to audio players in particular, or to any ear covering? I'm curious (1) whether that applies to balaclavas for warmth in the winter and (2) whether an earplug in my left ear would be allowed. As a daily biker, it's astounding how deafening trucks/motorcycles can be.