Researchers found that major chords and songs in major keys evoke positive emotions while minor chords associated with songs in minor keys can bring on sadder emotions.
But these associations may not be universal; people in some communities, like Papua New Guinea, do not associate chord progressions with emotions in an identical fashion.
Intervals
Intervals in music refer to the distance between sounds that are played one after the other – either consecutively (melodic interval) or simultaneously (harmonic interval). A basic interval is an octave containing C, E and G notes – and major triad chords often sound happy as their first, third, and fifth notes from a major scale appear within these chords.
Why we associate minor chords with sad music and major chords with happy music is unknown, though perhaps related to growing up listening to songs with these chords and thus becoming familiar with how they make us feel; though this could just be speculation.
Other elements such as the tempo, timbre, rhythm and melody of a piece can have an influence on our perception of it as well. Research indicates that associations between chord progressions and emotions do not correlate directly with musical keys themselves since cultures like Papua New Guinea do not experience Western-influenced chord progressions in the same manner.
Scales
A scale is any graduated sequence of notes or tones arranged into an octave, dividing into major and minor scales by an interval known as an octave. Major scales contain major thirds while minor ones contain minor thirds – these intervals determine whether a chord sounds happy or sad.
Musicians and non-musicians in Western societies typically associate major chords with happiness, while minor chords have been linked with sadness. Neuroscientists have also discovered that specific harmonies stimulate certain patterns of activity within the emotional centers of our brains.
How do we account for these polarised perceptions? According to guitarist Adam Neely’s theory, it lies with our perception of interval sizes: larger intervals are perceived psychologically as brighter. While the major scale has seven notes while minor scale has five, major pentatonic is an integral chord used in blues, folk and rock music and sounds brighter even without those missing tones; major pentatonic chords play an integral part in blues, folk and rock genres alike.
Harmonics
A chord contains multiple harmonics. These harmonics vibrate at different frequencies than its fundamental, for instance the second harmonic resonates an octave higher while its third counterpart vibrates an octave lower.
Chords that contain multiple harmonics often sound fuller and richer. For instance, Cm6 sounds fuller and richer than Cm7 due to the sixth harmonic being five degrees lower in pitch.
Combining intervals of the scale with brightness or darkness of chords gives songs featuring major chords a happier sound – likely why most pop music uses major chords. But it is important to remember that minor chords can still sound happy – for instance Imagine by John Lennon contains the minor seventh chord; similarly, using same chord progression in minor key can convey feelings of melancholy or sadness.
Culture
Musicians will agree that chord progressions written in major keys generally sound happier. This has to do with the relative sizes of intervals within a chord or scale: wider intervals tend to sound brighter. Furthermore, culturally it can also play a part; people familiar with Western-style music will know that major chords give them joy while minor ones make them sad.
Researchers put this theory to the test by asking a group from Papua New Guinea with little exposure to Western-style music to listen to excerpts of musical pieces, indicating their emotional state through a simple rating scale (happy/sad). Furthermore, musicians and non-musicians in Sydney were asked to do the same.
Results were quite telling: people with experience of Western style music correctly predicted emotions; those without as much or any exposure guessed invertedly, suggesting that cultural memory combined with chord progressions and natural harmonic overtone series is what leads us to associate major chords with happiness and minor chords with sadness.