Maybe I'm not supposed to get it, since I'm not autistic, but why does turning off the radio with an annoying sound reduce energy? From my perspective, I can't find any logical correlation between the choices made and the outcomes.

Seems like turning off the annoying sound would be a good thing. This, unfortunately, just makes autism seem inscrutable and something I will just never understand.

It is mental effort to have to recognize what is triggering you and to take positive action to fix it. The radio is more symbolic of having to do it 40 times a day across all the things you find triggering, or having to find ways to live your life outside common neurotypical ways that take more energy. For example, finding dishes clinking to be really triggering means I have to use ear protection to unload the dishwasher, and if I can’t find ear protection that I have to spend time looking around for it, and now dishes have taken me 3 minutes longer than it would someone else. Over a dozen instances a day of something like this adds up