Why do people think that the quality of music is declining?
When it’s simply not true.
Imagine that 100 songs are produced annually. 10 of these are “good” and 90 are “bad”. This is true for Year 1 as well as Year 2. If a listener in Year 2 listens to all songs from Year 1 and Year 2, he’d conclude that the quality of songs is the same in both years (10% good). If, on the other hand, he hears only the good songs from Year 1 and all the songs from Year 2, he’d conclude that Year 1 produced 100% good songs while Year 2 produces 90% crap. Thus, music quality appears to be declining.
Good songs (“timeless classics”) survive – bad songs do not. When you listen to music from the 60s or 70s, you’re listening to the good music from the 60s and the 70s – music that your friends recommend to you. On the other hand you hear (courtesy VH1 and MTV) all the (popular) music that was produced this year, good and bad. Thus it appears that a higher proportion of the music produced in the past was of good quality. Joel Waldfogel (see the link above) adjusts for this survivorship bias and reaches the opposite conclusion – thanks to the spread of technology music quality is improving.