Greer found that timbre also matters: A note played on a piano versus a violin triggers different emotional tones in listeners. You hear this often in solos that you would consider “raw” or “tortured,” as in Radiohead’s “Climbing Up the Walls,” where Thom Yorke sings dissonant notes and his strings are purposely mistuned a quarter-note off to further the clash. In particular, dissonance in minor keys really tugs on the heartstrings. We find harmonic complexities to be stimulating. When that hits, “the listener really feels an emotional response-it triggers an emotional heating of sorts,” says Greer. For example, many songs open with one singer and one instrument (often a guitar or piano) before a huge band entrance. Complexity. Your body is stimulated by the addition of a new instrument or harmony, and it’s the juxtaposition of noncomplex and complex that triggers your emotions.For example, switching from a minor to a major key creates a sense of release that makes you feel happy, such as in the chorus chords of Pharrell Williams’s “Happy.” This is why songwriters usually modulate between major and minor dozens of times in three-minute pop songs.

Key. You already know that chords in major keys sound happy and chords in minor keys sound sad, but it’s the moment of contrast between the two that triggers your emotional response.

candidate at USC’s Viterbi School of Engineering, wanted to map which music causes specific neural, psychological, and emotional responses, so he had 40 volunteers listen to happy and sad songs while undergoing brain scans, heart and sweat monitoring, and subjective emotional response questioning.

Emotions of the music keys