i think the error that a lot of these studies make is that they compare serious music before 1955 to folk music after 1955. there's certainly been a merging of the ideas starting with zappa and the beatles and pink floyd. but, i really don't think these differences come out if you do like comparisons: debussy to stockhausen or nirvana to ledbetter or bjork to billie holiday or one direction to traditional nursery rhymes.

the only thing i'd pull out as probably being substantially different is that you previously wouldn't expect people in their 20s, 30s, 40s and 50s to experience the kind of arrested development they experience today. they would have grown out of the nursery rhymes, not latch on to successive ones until they're grandparents. so, the real issue is the juvenilization of society.

www.smithsonianmag.com/smart-news/science-proves-pop-music-has-actually-gotten-worse-8173368/?no-ist