Researchers have confirmed what many suspected - pop music over the last five decades has grown progressively more sad-sounding and emotionally ambiguous. They analyzed the tempo (fast or slow) and mode (major or minor) of the most popular 1,010 pop songs identified using year-end lists published by Billboard magazine in the USA from 1965 to 2009. Tempo was determined using the beats per minute of a song, and where this was ambiguous the researchers used the rate at which you’d clap along. The mode of the song was identified from its tonic chord - the three notes played together at the outset, in either minor or major. Happy sounding songs are typically of fast tempo in major mode, whilst sad songs are slow and in minor. Songs can also be emotionally ambiguous, having a tempo that’s fast in minor, or vice versa.
The researchers found that the proportion of songs recorded in minor-mode has increased, doubling over the last fifty years. The proportion of slow tempo hits has also increased linearly, reaching a peak in the 90s. There’s also been a decrease in unambiguously happy-sounding songs and an increase in emotionally ambiguous songs.