My hearing isn't great anymore (in my forties) and unless I am in a quiet environment, I don't hear the beeps. The pitch is a real challenge.

I did go to a store with my family recently and when I tried to lock the car, it kept beeping at us and we discovered the power was still on so we repeated the following several times to sink it into our consciousness

"Several beeps means the power is still on. Several beeps means the power is still on.......etc"

Of course, it was a quiet parking lot and if it weren't I wouldn't have known til I came out from the store!