Further hearing protection is afforded by keeping your mouth closed when firing.
I started doubling up at one point in time to work off a nasty flinching habit that I had developed. I took a couple shots with my mouth open, and that was shocking! I never really considered the fact that those sound waves can come right to your ears through the mouth. That might be worth considering for your wife, if she's mouth-agape in concentration on her shots or something. I'm certainly not implying anything, I've just seen people do all kinds of funny stuff when they are going through their shot plan.