One major reason for the decline in musical literacy has been the rapid decline in home music-making by amateurs (four-hand piano, voice and piano, chamber music for two three or four people). This active musical participation has been largely replaced by the passive activity of listening to recorded professional performances.
Leinsdorf had started as the music director of the Boston Symphony about the time I started college in Boston in the early '60's. At that time they had very low prices for their open rehearsals for the BSO, and I regularly attended those. Leinsdorf treated them as almost like real performances, so we got to hear the entire concert, just as if we were paying the big bucks to hear it. One day Jean Martinon, who would become the music director of the Chicago Symphony, was the guest conductor. He treated the rehearsal as a real rehearsal, with many starts and stops and working on a few difficult sections of the pieces, again and again, and we never heard a complete performance of any of the pieces in the program - a big shock to the audience.
Not sure of all the reasons of the downturn in music in the home. Surely one major cause has been the elimination of most of the music performance programs in schools. When I was growing up, the school band, orchestra, choir, etc. were big programs starting in junior high through high school. Many people got their start playing instruments through those programs. I took piano lessons starting in 3rd or 4th grade and would play in recitals and even accompanied one of my classmates when he sang a Schubert Lied at the state music competition. My wife has been an avid amateur pianist all through her life and we have a couple of groups of amateur pianists who play monthly for each other in our homes. We've had chamber music groups play in our home and host home concerts annually with members of the San Francisco Symphony. Very much like in the old days in Europe.
Levitin is not only a neuroscientist, emeritus professor at McGill in Montreal, but also a four time New York Times best selling author. We talked with him last week at our local book store, where he is on a world wide tour. It also happens that he lives and grew up in our town. What is most interesting for audiophiles and music lovers, is that he is an aging rocker. He started with a rock band in junior high, dropped out of MIT to join a band, founded a record company, 415 Records, and sold it, all by the age of 30. It was then he went back to college (Stanford) and earned his degree and then to the University of Oregon for his PhD. The day before we saw him talk, I was going through my master tapes (completely unrelated to seeing him) and was researching the Steely Dan Katy Lied album. Turns out Levitin has a credit in the wiki article on the album. I asked him about it and he told me that he was hired along with another person to produce the reissues of the Steely Dan albums they rereleased in the early 90's. Look at his wiki article. He has been touring with Judy Collins and plays in jazz bands from time to time. Very engaging writer also. Well worth the read if you are getting up there like me.