When my phone is full and still on the charger, the whine is intolerable. Three chargers so far have done this. Not sure if it is the same thing. I consider my hearing sub par and I'm in my mid thirties.
In extremis, you can open up a charger and pot the coils yourself with hot glue, epoxy, or some other nonconductive polymer. Just be sure to disconnect it from power first, lest you inadvertently get your own batteries charged.