In the past several years I have had more of a problem discerning whether a vehicle was coming up behind me than I did when my ears had fewer miles on them. I have not yet failed to hear an actual vehicle when one has been overtaking, but I frequently glance back because I think I hear the first telltale shift in the wind noise that indicates the approach.
I hoped the Cat Ears would address this problem. Eventually they might. In the meantime, they may have made it slightly worse. Because I no longer hear a strong rush of wind noise, I hear lots of other noises that blend into a different steady rush in a slightly lower register. This lower register seems to match more closely the altered pitch of the old wind noise as a vehicle moves into the turbulence a few lengths behind me. I look back more than I did before, because I'm not accustomed to the new soundscape yet.
A mirror might help, but I don't like how any of them mount to the bike or rider. A rear-view camera with a monitor on the bars would be perfect. It would also be expensive and cumbersome. Well, maybe not too cumbersome, as a quick search of wearable video cameras will demonstrate. There's even the Owl 360, specifically marketed as a rear-view camera for bicyclists. It's sort of affordable, as such things go, at $179 - $199. I don't have a hankering right now, but if I developed one I would have to remove one other piece of nerd rigging for any new piece I add. So what can I stand to live without? Other than most of it, that is.
The Cat Ears have improved communication when I'm riding with someone else. The incidence of, "Huh?! WHAT?!" has dropped markedly. It's not like being in a quiet room together, but it is definitely better.