Harmony occurs when two or more notes are played at the same time. when it is formed with two notes, it is called Dyad. when three notes or more are played together, it is called Chord.
However, just because two notes (two pitches) are sounded together does not mean the music is harmonious which is played with harmony. When the sound is harmonious, it sounds pleasant.
When music is with harmony and nice sound, we called it Consonance
When music is not harmonious and even ear piercing, we called it Dissonance
By science, there some formula for harmony intervals such as
- Unison (same notes in different octaves)
- Perfect 5ths and 4ths such as G and D or G and C
- Major and minor 3rd such as F and A or F and Ab
- Major and minor 6ths such as D and B
Examples for harmony in three intervals
- C major triad C, E and G
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