Are you ever in the mood for a happy, up-tempo pop song? If you’re American and happen to hear one on the radio, the (6) _____ are it was recorded quite a long time ago, according to a joint study (7) _____ out by scientists from universities in Canada and Germany, Glenn Schellenberg and Christian von Scheve set out to examine emotions conveyed by music in the American pop charts between 1965 and 2009. They classified songs (8) _____ pace and key they were composed in. People generally (9) _____ faster songs in a major key with happy feelings, and slower songs in a minor key with darker emotions. (10) _____ speaking, in the 1960s, the charts were dominated by upbeat music, but over the next five decades it (11) _____ to a more melancholic, complicated sound. Intriguingly, (12) _____ the last decade, the proportion of emotionally ambiguous songs (sad-sounding but fast, or happy-sounding but slow) has significantly increased. The researchers believe these trends may give interesting (13) _____ into more general social changes. They speculate, for instance, that people may now engage with more varied emotions. Giúp mình gấp nhé