Good point mate. However I have it on good authority that the PL in its musings have already come up with two possible solutions to this problem. The first is to have a special Refmask with a built-in whistle properly sealed of course using silicon or something. I am about to go to my shed to knock one up for the PL to try out using one cup of the wife's bra. The second solution is to dispense with referees altogether and just use VAR especially since VAR has been so universally loved and efficiently used since its inception . The VAR ref would "whistle" by activating a loud klaxon installed in all grounds.
Hard to choose between two such commonsense solutions.
Maybe they will give the ref a horn off a clowns car.