An agreeable sound

Look, we all just make crosswords to talk about stuff we’ve been into lately, and if you don’t know 20-Across or 56-Across, well, treat yourself. Spoilerrific links after the puzzle!

OK, spoiler-y links: 5A, 20A, 56A (but also!), all about 62A, 67A, 13D, 26D, and 53D/53D.