Triads in Minor Keys 3: Melodic Minor

In this video, Dr. Anthony Fesmire presents the diatonic triads found in the harmonic minor scale. This video is part of a hybrid Music Theory I class taught at College of the Desert. Video Text In this video, we will learn the triad types that are derived from the melodic minor scale. To form the melodic minor scale, we begin with natural minor. Here is the A natural minor scale. All natural minor scales use the notes from their key signature. Since A is the relative minor of C major, the A minor key signature has no sharps or flats. To create the A melodic minor scale, we raise the sixth and seventh notes of the scale by one half-step, so the F become F sharp and G becomes G sharp. For the descending form of the scale, we return the sixth and seventh notes to what they were before they were raised, making the descending G sharp, G, and the F sharp an F. So the descending melodic minor scale is the same as natural minor. Since we know the chords from natural minor, we will only be concerned with the ascending version of melodic minor. We can now follow the same process that we followed for creating the chords from the major, natural minor, and harmonic minor scales. We will add two notes in stacked thirds above each note of the scale giving us line-line-line or space-space-space combinations. To come up with the correct chords for melodic minor, we need to be sure that any chord that has the raised sixth or seventh of the scale, in this case F sharp or G sharp, also has that note. So we will add the following F sharps to the second and fourth chords and G sharps to the third and fifth chords. Now I can name each triad by checking for the distribution of thirds. Since the root of the first chord is A, this is some type of A chord. By determining the intervals between the root and third and third and fifth, we can name the chord. From A to C is a minor third, or three half-steps, and C to E is a major third, or four half-steps, therefore, we have an A minor triad. For the next triad, we have B to D as a minor third, or three half-steps, and D to F sharp as a major third, or four half-steps, therefore, this is a B minor triad. For the next triad, we have C to E as a major third and E to G sharp as another major third, therefore, this is a C augmented triad. If we continue up the scale using the formulas for triads, we will determine that the fourth chord, with D, F sharp, and A, is D major, the fifth chord with E, G sharp, and B is E major, the sixth chord, with F sharp, A, and C, is F sharp diminished, the seventh chord with G sharp, B, and D is G sharp diminished, and this returns us back to A minor; a chord that we do not have to rewrite since it is the same as the first chord. Now that we know the names of the chords in A melodic minor, we can determine the roman numerals. Since A minor is the first chord, we will use the lowercase i. The i shows that it is the first chord of the key, and the lowercase shows that it is minor. With the B minor chord being the second chord in the key, it will get a lowercase ii roman numeral. With C augmented being the third chord in the key, we will use an uppercase III with a plus to show that it is the third chord in the key and it is augmented. Four is major and uses an uppercase IV. Five is major and uses an uppercase V. Six is diminished and uses a lowercase vi with a circle, and seven is diminished and uses a lowercase vii with a circle. What we have discussed to this point with the creation of triads in keys and their roman numerals all follows regular formulas for naming the chords and identifying roman numerals. With music theory begin a science that strives to explain how sounds work together in the context of the artistic expression of a composer, improviser, or performer, it is nowhere near a perfect science. Here is one case in point. For the roman numeral for the sixth chord in melodic minor we use a lowercase vi and a circle to show its position in the scale and its quality. Since the root of the chord is a raised from what it is in natural minor, the convention is to call this chord sharp-six-diminished. This does not necessarily mean that the chord will have a sharp on the root: in this case, sharp simply means that the root was raised by a half-step from what it was in key signature for natural minor. Where this gets a little confusing is with the seventh chord of the scale. Here we have a chord where the root has also been raised by a half-step from what it was in the natural minor key signature, but it is not the convention to call this sharp-seven-diminished. The reason being that viio is the common chord from the seventh position of a minor key and it is understood that it is based off of the raised seven of the scale when it is identified as viio. Sharp-six-diminished is not a common chord, so it receives a special designation.