A question on harmony, or perhaps the antithesis of harmony:
What do people mean by “dissonance” and other such terms when talking about chord changes?
Dissonance, according to the dictionary, is “an inharmonious combination of sounds; discord; any lack of harmony or agreement.”
When we listen to music, certain notes sound pleasing when played together. For many people, the interval of a major third (C and E, for instance, or G and B, etc.) is perhaps the most pleasant, or harmonious sound.
Dissonance is when we create a sound that is not harmonious. There are degrees to how harsh the dissonance can be. If you were to play a C (5th fret, G string) and a C# (2nd fret, B string) together, it would sound as if the notes are clashing.
In a sense, they are – you feel that this combination of notes wants to turn into something else. It’s almost as if you’ve caught them in mid-metamorphosis. Play these notes again and now slide your finger on the C down to B (4th fret, G string) and at the same time slide the C# up to D (3rd fret, B string). Can you hear how the dissonance completely disappears? It’s the interplay between dissonance and harmony that helps to add a dramatic, almost dynamic aspect to a song.
Dissonance can be created in countless ways. You can add a dissonant note to a chord (even via a melody or bass line), you can play one chord on top of another, or you can play a string of chords while holding one note steady in the bass.
But the thing to remember is that not everyone hears the same sorts of dissonance. It’s a matter of what you’re used to. That C/C# thing we mentioned earlier? A jazz player would write it off as a C#maj7 and might not think of it as dissonant at all.
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