Their theoretical constitution is very simple : With C Maj scale for reference (old Ionian mode ) we play one octave starting on each degree of the scale
Names are objectionable due to confusion in their origins.
Thus the mode phrygian (E) mode in the middle age was called Dorian under Platon .
Futhermore Greek names do not refer to ancient Greek scales which were descending but to ascending scales from probable byzantine origin.
Another difficulty stems from Gregorian songs, from which church mode were born,that are under two forms
- -The authentic form that begins by the finale (our tonic); but the scale may start on one degree below ; so Dorian mode (from D to D) may extend from C to D
- -The plagal form that starts a lower fourth below the authentic one. The name is then preceded by the prefix Hypo so Dorian is the authentic and Hypo Dorian the Plagal form( from A to A) of the same mode
It is simpler to consider octave either as the association of
a pentachord and tetrachord that share a common note (authentic mode )
- or an tetrachord and a pentachord ( plagal mode)
. The finale is the first note of the pentachord in both forms
Table 2 Mode Authente et Mode Plagal
Table 3:Shows ambiguous span
Some modes share their range :The authentic phrygian mode (E ) is similar to plagal Aeolian mode (hypoéolien) , or authentic mixolydian mode similar to the plagal ionian mode.
The difference between authente and plagal rests upon the teneur (our dominant); but here again things are not so simple:
In authentic mode , the teneur is normally a fifth above THE FINALE but if the teneur is B it becomes C
In the plagal form, the teneur is normally a fourth above the finale but it might be a third or a sixth above the finale .
Table 4: Finales and teneurs
To crown it up accidentals (especially F# and Bb)was gradually introduced to set up the semitone tone of leading tones .
Others accidentals might appear in the descending forms . All those changes led to the reduction of the number of modes to the only major and minor modes of the tonal system.
The 14 modes previously listed are pure theory and don’t reflect the confused historical reality.
Classically there are only 8 byzantine modes ( D E F G ) under the 2 forms.
For simplicity we’ll keep the nomenclature of scales without accidentals of table 1, currently used especially in jazz music.
Characteristic Notes and key signature
Each mode has a characteristic note except the Locrian mode that has two characteristic notes
This note is said characteristic because it makes the difference between the tonal scale and the parent C Major scale.
For example the Lydian mode starts on F and runs on one octave without alteration so it is different from F major which has a Flat (Bb) . The characteristic note is therefore B=4th degree of the F maj scale.
For the minor modes (dorian, phrygian et locrian) one must reason from the major relative
For example the phrygian mode (mode of E) is a minor scale without alteration while, E minor is the relative G major scale with a sharp(F#) ),the characteristic note is therefore F: second degree of the E scale
Remark Aeolian mode has not a characteristic note since it is the relative of C major (no accidentals)
Let’s draw a table to enable characteristic note finding and transposition .
1°)From tonal notes CFG and their minor relative ADE, plus B by assimilation to minor mode,our table looks like this
2°) Key signature adaptation
F major scale is a fifth below C Maj To transpose the F major scale to C major one must add a fifth.
The trick is to count the number of degree from the tonic (N1) to C . Reporting the number of degree from C give the new key signature
In minor modes the goal is not C but A
We can now complete our table
- Mode of Fa :Key signature of G major 1#
- Mode of Sol:Key signature of F major 1b
- Mode of Ré: Key signature of E Minor=G major 1#
- Mode of Mi: Key signature of D Minor=F Major 1b
Notice : characteristic notes are either F or B (the triton of CM)
Locrian mode is particular since its tonic fifth is diminished . It’s origin is not a relative major scale like other minor mode but its third being minor it can be assimilated to a minor scale to used our trick ( from B to A = 7 degrees: A +7= G Minor= 2b )
1°) Write a mode in another tonality
Our table give the direction to the key signature modification.(Toward more flats/less sharps or More sharps/less flats)
1-to write an A lydian scale ( F mode)
– Lydian=Major mode so we have to adapt A major scale(3#)
-our table reads 1 # to add to to scale
So A lydian is a scale with 4# (starting on A)
2-To write a Eb lydian scale (F Mode )
– Lydien =Major Mode so we have to adapt Eb Major scale(3b)
-Our table indicates +1 # so flats go opposite (-1b)
Eb lydian is a scale with 2 b (begins on Eb)
3-To write a G phrygienne scale (E Mode )
– Phrygien =Minor Mode Mineur – we have to adapt G minor scale â€“Major relative Bb= 2b
-our table read+1 b
G phrygian is a scale with 3b flats and start on G
Caution the reference minor scale have no accidentals(but the stuctural one of the major relative) and therefore no leading tone
Building a kind of sliding rule will make things easier especially for minor modes.
1°) Writing a mode in another tonality (Key center)
The fixed part( règle fixe) is a fifths series from 6b to 6 # on the upper part and the corresponding tonalities on the lower part
The movable part( règle mobile) is the same fifths series with a colored part indicating the seven modes .
By coinciding the note of Mode from the movable part with 0 accidentals ( C) ,key signature are given for tonalities on the fixed part .
With our former example A Lydian scale ;from the movable part align F= Lydian mode with O on the fixed part; Â from A on the movable part A we reads 4# on the fixed part
Same thing for minor mode : D ( Dorian mode ) facing 0 accidentals (CM), A Dorian is a scale with 1#
2°) Identifying a mode from a tonality
We use the same fixed part of our sliding rule and reverse the fifths series on the movable part,using only the 7 modes (from F to B).
The tonality is on the movable part facing 0 of the fixed part. The movable part lists the 7 modes coinciding with key signature on lower fixed part
Example A scale with 1#.What is the mode?
Align A from the movable part with 0 on the fixed part, the 1# column reads D on the movable part
So A scale with 1# is a A Dorian scale