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This is a figured bass exercise I just completed and towards the end you will see a IV65 going to a V65. This progression has two diminished 5ths in parallel motion. Is this acceptable part writing and would such a motion be correct common practice harmony pedagogy? enter image description here

Edit: It is very hard to find information about this on the internet but I did find this which says that diminished 5ths are not prohibited because they are not parallel intervals and if none of my textbooks speak of this prohibition then I think my part writing should be correct.

enter image description here

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  • In the context you are working, are there any prescribed ways of treating dissonances? If so, you must make sure to follow them here. In the contexts I am used to do harmony exercises like those, the parallel diminished fifths would not be acceptable due to the diminished fifths not being treated. May 11 at 12:49
  • So how would you write ii°6 or ii°7 to V? Not all diminished 5ths or augmented 4ths resolve
    – armani
    May 11 at 13:24
  • If you can only treat dissonances by suspension or passing tone them there I don't think there is a way to voice-lead that progression, as the diminished fifths is a dissonance in both chords. You would have to resort to other treatment methods, and those vary depending on the textbook and on the point the exercise in on the textbook. May 11 at 14:28
  • So, to give a full answer I would have to know more about the context in which you are doing those exercises. May 11 at 14:29
  • Here is the figured bass ibb.co/Qf8gmNQ
    – armani
    May 11 at 15:47

4 Answers 4

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Whether things like parallel diminished 5ths are allowed is a abit of a grey area. In any case the answer depends on what you mean by acceptable. It certainly is not good part writing, as it simply shifts the same chord up by a whole tone. Instead of going for this

enter image description here

you might rather want to do something like this:

enter image description here

EDIT: With regards to the restraints mentioned in the comments you might want to do something like this:

enter image description here

Or if you want to have all 7ths resolve correctly something like this:

enter image description here

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  • Thank you but the soprano tone on the next I chord in the following bar is included as F# so I cant use an E in the soprano. E would resolve to D#. Having said that, do you have a solution other than mine? I have a feeling they put that soprano tone there to force me to not have E in the v65 chord. Only with ^5 in the soprano can I have ^5 in the I chord that follows.
    – armani
    May 11 at 13:29
  • lots of good part writing shifts chord shapes up or down so long as there are no perfect intervals in the progression... what about 63 chords?
    – armani
    May 11 at 13:35
  • @armani If you shift around 63 chords in four part harmony you nescessarily get parallel octaves or fifths. Also I wasn’t aware that there were restrictions on the upper voices. Could you share these restrictions? It is hard to think about this if I do not know what you actually need to fill in.
    – Lazy
    May 11 at 14:53
  • here is the figured bass, you will see what I mean ibb.co/Qf8gmNQ
    – armani
    May 11 at 15:46
  • @armani I have posted some suggestions for this as edit.
    – Lazy
    May 11 at 18:16
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Is this acceptable part writing and would such a motion be correct common practice harmony pedagogy?

This is an exercise. The instructions in the linked scan say "be sure all dissonances are approached and left correctly."

Those instructions don't necessarily reflect your question. Musicians did things in the common practice period that did not always follow the strict teachings.

I think the parallel 6/5 chords you have are probably OK for 18th century style harmony - it's not parallel perfect intervals, and inverted chords seems to mitigate the general rule against parallel motion/root progression by step - but your part writing violates the rules of the assignment, because you aren't preparing/resolving the dissonances.

The given bass is...

enter image description here

...where I see two main "problems". The bass results in root progression by ascending step, and the soprano requires F#5.

A common rule of thumb is when roots progress by step, move the upper voices in contrary motion to the bass. But that doesn't really work so well in this case, because of the F#5.

Another thing to try is work backward.

The simples way to precede the F#5 is by repeating it, which will also give us the 6 of the 6/5 figure...

enter image description here

For the chord before that the simplest thing seems to just use parallel sixths, that gives use the two chords of the sixth on beats 3 and 4, given the bass is playing the thirds of the chords, harmonizing about with sixth above provides the chord roots, that's a solid harmonic "skeleton" for the outer voices...

enter image description here

The B minor chord before that could be realized a few ways in the top line, lets try filling in the inner voices for what we have so far before choosing how to voice the B minor chord.

I'm not sure why, but my first thought is to find out how the chord seventh should fit in, also with a progression of IV V I realize the subdominant degree will first be a chord root for IV but then become the seventh of V, and that make me think "hold that tone in some voice", and then of course it will resolve to the mediant degree.

enter image description here

Let's try to complete some of those chords with four parts...

enter image description here

A bit of trial and error to avoid parallel octaves and I voiced the B minor chord as...

enter image description here

I think that should all be OK.

D5 the dissonant seventh of E7 on beat three is prepared as a repeated tone, and it resolves down a step to a third above the bass.

E4 the dissonant seventh of F#7 on beat four is prepared as a repeated tone, and it resolved down a step to third above the bass.

Again, this is all to fulfill the requirements of the assignment not necessarily meant to represent all common practice music. I think you can enjoy some artistic license and use what you wrote and still be within 18th century style, but you might get points deducted on your homework!

About the catalog of motion types from the textbook, I think it's easier to keep in mind one simple rule:

  • Similar motions, which includes parallel motion, to only imperfect consonances.

ALL other relative motion to consonances is OK.

Dissonances in any case are to be prepared and resolved.

From the one rule (that tells you what to do, rather than what you cannot do) it follows that perfect consonances should be approached by contrary or oblique motion.

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  • Thanks Michael. Very nice as always. The only thing is that while it is fine working backwards, you might want to consider how you are going to end up with that voicing on the Bm chord. It wont work so nicely in this case to get to that voicing from an open 3rd position Bm.
    – armani
    May 12 at 9:59
  • You are spot on about my exercise not following the assignement requirements and I should have reealized that my dissonances were not resolved. It would have cost me some marks if I actually was going to have my work checked
    – armani
    May 12 at 11:28
  • Working backward is more of a single tactic. The thing I've seen in 'how to harmonize' sections of textbooks, and something I try with my writing is more of a sketching process: work outer voices before the inner voices, get beginnings and phrase endings set, then fill in the interior or phrases, if thematic material will be reused in some way, sketch that in to the right structural points, etc. etc. Hopefully, if your initial sketch of the important points is good, but you find some problem comes up, you can fix in the details of only the filler material, rather than your principle ideas. May 12 at 21:02
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Consecutive diminished fifths which move chromatically can occur in successive dominant 7th chords that are a perfect fourth apart.

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  • Is that towards the end of the course? I have just gotten to diminished 7 chords in my tonal harmony course which is before the chromaticism section
    – armani
    May 13 at 15:44
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Yes

In my many years of struggle with harmony exercises I have on occasions been made aware of the fact that my answer has been saved a failing mark by the fact that my parallel fifths where in fact diminished parallel fifths.

I have more times though just got a red line striked trough my answers for having the verboten fifths.

Better just to avoid parallel fifths of all kinds.

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