How do they know he needs those?

I was carrying Peter in a sling, and he was wearing his cute blue hearing aids when i was approached by a stranger who asked me out of the blue "How do they know he needs those?". I know she was just curious, and that she meant well, and maybe my standards are too exacting, but I felt like an "Excuse me,...." or "I just noticed, and I was wondering..." would have been a more polite approach. Ok, skip over the etiquette lecture. I figured it's good practice for all the questions I'm sure will come if/when my little guy has bionic ears. I answered politely, and hoped to spread some knowledge about the impact of Universal Newborn Hearing Screenings. I explained how the tests in the hospital are able to measure a newborn's brain's reaction to noise (earbud, electrode on the forehead) and that they weren't asking a baby to "raise your hand when you hear the beep" ;) I didn't get into the intricacies of the more in-depth ABR or otoacoustic emissions test, as the woman was already gushing over how lucky he was that we were able to catch the hearing loss early. I agree. We were lucky our state has Universal Screening. We were lucky our child was born now, and not in an era where haring less wasn't diagnosed until 2-3, or later. We were lucky hearing loss is now treated in a family setting instead of recommending institutionalisation. We are lucky that insurance covers the cochlear implant that Peter is most likely a candidate for. We are lucky just because we have such a wonderful baby. The only bum luck was that the last governor vetoed a bill to require insurance to cover pediatric hearing aids. Peter is lucky that the expense didn't delay us in getting him aided, but I imagine there are plenty of kids who have to wait while their parents apply for grants, or hope to get loaners or used aids at a discount. How lucky I am strangers can come up and ask me about Peter's hearing aids!