I spent twenty minutes explaining to my roommate how the dishwasher salt works. Twenty minutes. Diagrams on my phone, the whole thing. He nods, says "got it," and then three days later: "Wait, so... do I need to add salt?" I looked him dead in the eyes and said, "Yes, exactly like I said before," and he went, "Oh, so it's like... salt?" I realized then that I hadn't been explaining badly—he'd just decided my voice was elevator music.