A scale is a particular combination of notes in music, usually played in ascending and descending order. Of these, the Minor Scale is a special scale, used regularly in making darker and sorrowful melodies. It is so called in western music while in Indian classical, it is called Darbari (in Hindustani) or Nata Bhairavi (in Carnatic).
In western terminology, it starts with the tonic key (say K) and then follows the pattern – K + 1 tone, + 1 semitone, + 1 tone, + 1 tone, + 1 semitone, + 1 tone, + 1 tone. For instance, if one starts at C, then the following notes complete the scale: D, E flat, F, G, A flat, B flat and C. On a piano, one can comfortably play this scale starting at D (where the only non-white note is B flat) or A (where there are all white notes).
Chords that fit this scale are as follows: (assuming it is the A minor scale)
i – A minor : A C E : this provides the base chord of any melody, songs usually start and end on this chord
ii0 – B diminished : B D F : this provides a dark effect but is not very popularly used
III – C major : C E G : this provides an easy transition into a happier melody, and to the C major scale
iv – D minor : D F A : this is a dark chord, used often
v – E minor : E G B : this is a dark chord, used to invoke sadness, determination or strong passion
VI – F major : F A C : this is used quite often to provide mild darkness
VII – G major : G B D : this is used very often to provide some counter-effects to the darkness
Note that the uses and descriptions of these chords are not completely covered above – this is a subjective issue and is limited to my viewpoint. Also if the tonic is any key other than A, all keys should be shifted by the same amount to get the new chords. For example, if we take the G minor scale where G is 1 tone below A, then chord i – G minor has G B flat D, chord ii0 – A diminished has A C E flat, etc.
Common chord sequences used in minor melodies are:
i – VI – III – VII
i – VII – i
i – VII – VI – VII
i – iv – v – i
Again, these are but a few of the infinite ways in which the chords can be used.
For effect, 7th and 9th chords can also be used. For instance, A minor7 can be used by adding G to the existing triad of A C E. This gives a more incomplete-sounding chord than A minor. Similarly, A minor9 can be created by adding both G and B. This is a more sensual chord, used in jazz and lounge music. The same can be done to chords iv and v (here, for good effect, the sixth note in the scale could be raised by 1 semitone). One could also make 11th and 13th chords by adding other notes. For instance, A minor11 has A C E G B D and A minor13 has the same with an added F# in the end (this F# is the sixth note of the scale raised by one semitone). Other interesting 7th chords can be created with the F# in use such as G major7 (which has G B D F#) and B minor7 (which has B D F# A). These two form good jazz combinations when used with A minor7. Finally, ii0 half-diminished 7 can also be formed if one adds A to B F D, etc.
Here is a summary of 7th, 9th and other extended chords as used in the minor scale:
i – minor can become minor 7th, 9th, 11th or 13th; 13th sounds particularly jazzy if one raises the sixth note by 1 semitone
ii0 – diminished can become half-diminished 7th (or diminished 7th if one raises the seventh note by 1 semitone)
III – major can become major 7th or 9th; perhaps even beyond
iv – minor can become minor 7th, 9th, 11th or 13th while sticking to the notes of the scale
v – minor can become minor 7th (or 9th if one raises the 6th note by 1 semitone)
VI – major can become major 7th or 9th; perhaps 11th may sound agreeable
VII – major can become dominant 7th (or major 7th if the 6th note is raised by 1 semitone)
One should not consider this list exhaustive since there could be many other possibilities.
Some interesting variations on this scale can change it to other interesting scales. Raising the 7th note by 1 semitone makes it the Harmonic Minor scale (or Kiravani in Indian classical). This makes the 5th chord more sorrowful or mildly passionate in some cases (it could have some different effect too; this is a subjective matter). For instance, in the A minor case, if G becomes G# everywhere then E minor is no longer v. Instead, E major is V. Then the – V – i transition is used more often. Also, this adds the possibility of the fully-diminished 7th chord involving the second, fourth, sixth and seventh notes of the scale (arranged in any way).
Similarly, if the 6th note is raised by 1 semitone, the scale becomes Dorian (or Bhimpalasi in Indian classical). This gives the possibility of several jazz chords such as the i – minor 13th and the v – minor 9th. This scale is said to invoke anger or passion. Finally, if the 2nd note is dropped by 1 semitone, the scale becomes Phrygian (or Bhairavi in Indian classical). This has its own set of interesting chords and is said to invoke deep sorrow or passion.
For completeness, here are the Indian notations for the minor scale (Darbari or Nata Bhairavi): Sa, Re, Komal Ga, Ma, Pa, Komal Dha, Komal Ni, Sa. Increasing the Komal Ni to Shuddha Ni gives the Kiravani scale. Increasing the Komal Dha to Shuddha Dha gives the Bhimpalasi scale. Decreasing the Re to Komal Re gives the Bhairavi scale. The rules of each Indian scale (or Raga) should be understood to involve more constraints than just the notes of the scale. Some of these include the order in which certain notes occur, the occurrence of certain phrases of notes, etc. It also makes a difference whether the notes are being used in ascending or descending order.
There is one more Western variation of the minor scale, known as the Melodic Minor scale. In this, while ascending, the sixth and seventh notes are both raised by 1 semitone each. While descending, all notes are unchanged. Hence, if one takes A minor, the ascending melodic minor scale has : A B C D E F# G# A. The descending melodic minor scale has : A G F E D C B A.
The minor scale is increasingly used in popular music nowadays. It is useful for any musician to know its properties.