Modal Cadences

Another difficult and confused topic . Ancient church modes were declamatory melodies, sang in unison, which   phrases  ended with fixed melodic and rhythmic formulas  and therefore had no cadence, as we understand with our tonal mind.
The first real cadences (clausules) appeared with polyphony which caused: the disappearance of modes
We can trace back modal harmonic cadences to the 19th century when composers tried to destruct tonality .However,Tonal culture is so deep-rooted in our mind that we want to make modal music a kind of tonal music transcription ( especially due to functional harmony).
Modal cadences are not conclusive as would be tonal cadences and are generally used to « add an transitory color » to a phrase.
But let’s first remind some tonality elements

 

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  • Tonality is based upon physical law of resonance with ascending harmonics that explain the Major triad.
  • Minor triad is more difficult to account for since there is not a descending resonance (in normal conditions ). However we saw (in the mirrors of the church modes) that an ascending major scale had its specific descending minor scale .( a major third above the major scale)
  • Tonal music consists of two modes based upon the third (IIIth degree) that determines
    -The Major mode ( III Majeur) which have 3 strong Major degrees (I- IV-V)
    -The minor mode (iii mineur) with 3 strong minor degrees strong (I- IV- V). However the 7th scale degree must be half a tone of the tonic to look like the major scale so the V th degree is altered and became a Major Chord.

Modern harmonic modality can be approach from different point of view.
The most intuitive is the minor mode without leading tone like the Aeolian mode with a minor Vth degre) for both ascending and descending scales resulting in change in degrees numeration . Cadence traces tonal cadence (v-I) for ascending scale or plagal (iv-I) for descending scale

We may consider semi tones as  leading tone : ascending LT B-C and descending LT F-E

According to the slope direction , two possible dominantes and two possible leading tones are available.

Remark :In tonal music progression B -C, B is leading tone because the semitone leads to a strong degree (The tonic ) while F is not a leading tone because it leads to a weak degree (III).

In the tonal progression F -E, F is not a leading tone because the semitone lead to a weak degree however E,as  descending mirror, is the  tonic and therefore a strong degree : thus F becomes a descending leading tone .

Let’s place a triad on the Vth degree of each scale in ascending and descending forms


Among those V degree chords let’s select those with one of the two possible leading tone F or B which is not at the bass

Besides the ascending Aeolian mode,only two chords appear

  • ii from the original C maj scale(Dm)
  • Dominant 7 chord ( GBD et B D F)

Dominant 7 chord appears under two forms GBD and BDF
BDF can’t be used due to the triton that would resolve to C maj.However, adding the sixth from the descending Aeolian scale enable the BDF chord to form a common dominant chord (DFAB) to Ionian(CM )and Aeolian (am) scale.

Notice that the sixth (B) placed on the( II chord ( dfa) is the leading tone of the ascending scale.
Let’s generalize the method by adding ascending leading tone to descending scale and reversely

  • Ionian Mode GBD ,resolving to CM, is ruled out and FAB as well since it adds a second dissonance to the triton leading to C major). The solution is FAC: creating a plagal cadence
  • Lydian Mode  is particular because we can neither use BDF which lead to C Maj scale nor CEG that would resolve to the F Major scale -The solution is GBDwhich contains the characteristic note and the leading tone altogether
  • Mixolydian Mode : The only possible chord is DFA with added sixth (B) DFAB

    • Aeolian Mode: we keep DFAB for its dominant chord characteristic in a plagal progression IV

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    We can of course use EGB but it’s less characteristic

  • Dorian Mode: Two chord progression are available (ACF) III6– and (GBD)IV-I
  • Phrygian mode The CM titron rules out the BDF chord) so we keep the ACF chord with the so called phrygian cadence II6-I

Another approach

As discussed in old church modes, Octave were divided into two tetrachords. There are different kinds of tetrachord:Four are part of old church modes (3 with perfect fourth and 1 with augmented fourth) and one perfect fourth tetrachord that does’nt belong to church mode:The harmonic tetrachord

The place of the semitones gives the direction of the slope,ascending on the right,descending on the left ,no slope in the middle
Considering Modes as two associated tetrachords

Lydian and Locrian modes do not allow two disjunct tetrachords and therefore those modes are the association of a pentachord and a tetrachord
Notice

    • -The central position of the semitones in minor tetrachord
    • -Ascending slope of the major tetrachord
    • -Descending slope of the phrygian tetrachord .

Association of two opposed sloped tetrachords

Lydian and Locrian modes concentrate semitones in a tetrachord
It should be observed

      • -The Dorian scale is a pivot scale with central position of semitones making this scale ambiguous with no slope
      • – The symmetry of th Ionian,Dorian and Phrygian modes E
      • -The inverted mirror ot Mixolydian and Aeolian modes

Conclusion

This last approach helps to choose progression according of the slope of the scale and a tool for counterpoint which is by essence related to mode

Another  hint

Let’ s write our scale as triads , not as a succession of triads but rather like a three voices counterpoint to take into account the respective location of semitones

The three minor scales share those three chords


The three Major scales share those three chords
However those chords do not necessary content the characteristic tone of the mode.
Adding a 6 th , 7th or 9th make things very interesting provide they don’t create the triton F-B which suggest the C scale.
We also may use medieval cadences discussed in
disappearance of church modes and the Baroque cadences which are similar to the medieval cadences but they may lead to a third interval (instead of octave or fifth)

 

 

Last Hint

We can make a tracing of functional Harmony according to two schools

1-The  Niedermeyer-Ortig’s french school  which uses tonal progression but chords  building abides by the mode (so V can be a minor chord)

2- The Persichetti’s american school which makes a distinction between  three kinds of chords

-The primary chords :The tonic chord and chords that contains the distinctive note of the mode.

-The secondary chords :chords that don’t contains the distinctive note of the mode.

-The Chords to avoid because of tritone  that lead to major mode.(It can be a primary chord with an added  7th  or 9th

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to summarize

Modal music is mostly melodic based on intervals and two functions Teneur (kind of dominant) and Final (Tonic). Its harmony is rather static and baffle functional harmony

Disappearance of church modes

Because church modes still prevails in numerous cultures, « Desertion » could be a proper word.

Actually the reducing evolution of mode that give birth to tonal music,based upon only two modes, is a very slow process that makes difficult to find a proper word to describe it.

There are many reasons that lead to the disappearance of modal scales.

    • One of the main reasons results from the way to avoid the triton F-B in polyphonies by lowering B, so it becomes Bb, or altering F into F#.
    • the second reason is a rule of counterpoint: an imperfect consonance(thirds and sixths) followed by a perfect  consonance is better approached by a semi-tone in one part and one tone in the other part
      A or B are better than C

      In three part this rule yields the double leading tones cadence which is of two kinds

      1-Machaut cadence:The two upper parts contain an half tone, opposed to the Bass:

      Adding a cambiata produces a Landini cadence


      2-Phrygian cadence:The two upper parts contain a tone, opposed to the bass

The third factor is the movement to a fifth lower at the cadence which created a forbidden dissonance seventh with the double leading tones cadence. So the authentic cadence is born: a major third resolving into an octave and a movement of fifth but leading to the disappearance of double leading tones cadence the F mode and G mode at the advantage of the C mode due to the necessary adaptation to avoid the dissonance seventh

To summarize we can say the main cause of the change is the growth of polyphony

* X th century with melody accompanied with parallel fifths or fourths.
* XI th century the melody starts and ends with the same note (named final, now tonic) and is accompanied with oblique motion which begins and ends in unison preceded by major second.
* XI-XIIth century introduction of the contrary motion with a major second as pre-cadential dissonance and a fifth added to the tonic
* The third is henceforth a imperfect consonance (formerly a dissonance) XIII th century cadence with double leading tone according to the rule of counterpoint edicted by Jean De Murs) The final chord has no third.
Consonance (8-5-4) evenly appear at the beginning of each « perfection » (group of 3 breves); there are non harmonic tones in short values between groups
* Ars Nova give up the rhythmic modes so consonances may appear on weak beat (XIVth century); the third is included into the fifth chord except in final position. Appearance of the movement V-I at the bass and the movement VII-I at the soprano {G-D-G}-{CGC}
* XVth Century: Instrumental music spread over the sonorous space with non modulating sequences on each degree. The third appears on the final chord so the authentic cadence is completed
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* XVI-XVIIth centuries is period of great change:alteration to approach consonance by half step resulting in 12 divisions of the octave and the polyphonies that jut out the octave impeded to distinguish the authentic and plagal forms-another cause of disappearance of modes Adoption of the Zarlino’s system with pure third and false fifths will yield new rules of counterpoint such as to forbid direct fifth and change the rule of third and sixth which become perfect consonance.