Spanish researchers Joan Serrà, Álvaro Corral, Marián Boguñá, Martín Haro and Josep Ll. Arcos researched recorded tracks between 1955 and 2010, also known as the Million Song Dataset, and the results are interesting…
Going through complex algorithms, they found popular music is getting louder, especially with re-releases with loudness increased, even with the volume level stays the same.
It also found that the so-called timbre palette becomes poorer, with the piano and guitar sounds with the same tune, also on the same volume level, have different tones, meaning less variety of sounds on modern pop songs.
Speaking to Reuters, Joan Serrà said:
We found evidence of a progressive homogenization of the musical discourse… In particular, we obtained numerical indicators that the diversity of transitions between note combinations - roughly speaking chords plus melodies - has consistently diminished in the last 50 years.
You can read the full report, titled Measuring the Evolution of Contemporary Western Popular Music here