So, what is a 2 note chord called? The technical term for a 2-note chord is a “dyad.” That said, a 2-note chord may also be referred to as a partial chord, power chord, double stop, or simply an interval. The exact terminology isn’t universal as some theorists argue that a chord must have at least three notes.
Can two notes be a chord? Typically chords consist of 3 or more notes. Personally I think of a chord as a cluster of notes that creates harmonic structure. Since harmonic structure can be achieved with just two notes, I think there are situations where 2 notes function as a chord.
You can learn more about common chord notation here.
Why Call a 2-Note Chord a Partial Chord?
It takes 3 notes to make the most common chord qualities of major, minor, diminished, and augmented. Because two-note chords can’t establish a chord quality on their own, it makes sense to think of them as “partial” chords.
For example, if a chord consists only of D and F♯ then it is ambiguous whether the chord will take on a major chord quality (like in a D major chord – D F♯ A) or a minor chord quality (like in a B minor chord – B D F♯).
Why call a 2-Note Chord a Dyad?
Three-note chords (like major or minor chords) are called triads while four-note chords (like 7th chords) are called tetrads. It makes sense to call two-note chords dyads since the prefix “dy” can mean 2.
Why call a 2-Note Chord an Interval?
The distance between two notes is measured as “intervals.” There are two types of intervals – harmonic and melodic.
A harmonic interval occurs when two notes are played simultaneously, while a melodic interval occurs when two notes are played one after the other.
In most cases it doesn’t make sense to think of a melodic interval as a 2-note chord. Why? Because then you would be thinking of any two consecutive notes of a melody line as part of a chord – which is an uncommon way to think about chords.
However if you see two notes played simultaneously especially in lower registers, it may make more sense to think about it as a chord.
When is a 2-Note Chord Called a Power Chord?
When two notes are played a perfect fifth apart on the guitar, that can be called a power chord. This chord is also referred to as a “5” chord, as in D5 which consists of D and A.
The main benefit of power chords for guitarists is that it is less muddy than a full triad. If guitarists use the distortion effect and include the third of the chord it may sound too messy.
Why Call a 2-Note Chord a Double Stop?
When a string player (violist, cellist, bassist, or violinist) plays two adjacent strings at the same time either plucked or bowed this is known as a “double” stop.
Sometimes this is used to develop harmonic structure, in these situations it especially makes sense to think of the double stop as a type of two note chord.
What are no3 chords?
No3 and power chords are essentially the same. Both of them omit the third scale degree from the chord, giving the chord an open or ambiguous sound quality. My sense is that No3 chords are used more often in piano notation, while power chords are used more in guitar notation.
There is debate over whether groupings of two notes qualify as chords. Under various circumstances a two-note chord may be referred to as a partial chord, dyad, power chord, double stop, or no3 chord.