I have a Cantus Firmus in D dorian mode that I am trying to write a 4 part counterpoint exercise with. In my textbook it says that since we have 4 notes per triad I need to double a note per triad to get a 4 voice voicing. It also says to double the degree 1, 4 and 5 of the scale I am in (it uses C major as an example which means the notes to double are C, F and G). However I get confused how this applies to modes? Since D dorian is part of the C major scale, do the same notes get doubled (C, F and G)? Or does being in dorian mean I need to use 1,4 and 5 of Dorian mode?
2 Answers
The 1, 4, and 5 being referred to are within the mode; that is, they are not 1, 4, and 5 of the corresponding major scale.
The general principle is not to double "tendency tones". Since you're dealing with triads, this means, in particular, the leading tone.
For example, in G - C cadence, you wouldn't double the B in the G chord.
This idea gets extended to say that you shouldn't double the third of a triad (the leading tone being the third of the V chord, for example). In C major, if one is dealing primarily with I, IV, and V triads, this means that 1, 4, and 5 (i.e. the roots or fifths of the triads) can always be doubled. However, 3, 6, and 7 are risky in that they could be the third of a I, IV, or V chord, respectively.
Doubling roots and fifths of major and minor triads is safe regardless the mode.
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So in D dorian which are the "tendency tones"?– user35708Mar 16, 2021 at 9:16
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@armani That genuinely deserves to be it's own question. But briefly, the idea of "tendency tones" relates primarily to major/minor Tonality, so in that sense other modes don't have tendency tones. Dorian, for example, has no leading tone. However, unless you're writing in strict Dorian, the usual practice is to raise the seventh degree at the cadence, thus creating a leading tone (i.e., a tendency tone), so you wouldn't double that.– AaronMar 16, 2021 at 13:23
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I totally get the concept of not doubling the raised 7th degree but that is only on the last chord. If my textbook tells me not to double tendency tones for all triads, then how will I know which those tones are? Yes I can use your method and just double the root and 5th but surely if my textbook is telling me not to double tendency tones then it must be known which those are.– user35708Mar 16, 2021 at 15:39
I'd like to add that the reason not to double "tendency tones" is that, because of the tendency, these "tend" to resolve to the same tone leading to parallel octaves. In C-major, (as an example), one doesn't double B as the tendency of B to move to C is felt rather strongly, especially as B is the third of the dominant. I know little about modes but the same ideas should apply. Tones in major or minor or modal tend to resolve by half-step if possible to another diatonic tone. I'd guess that (using the "white" notes from the natural hexachord) that moves of B to C, C to B, E to F, and F to E can have trouble with parallels.
The entire point is to keep the voiced independent. (In fact, in my stuff, my biggest problem is parallels between bass and melody. It's even worse when improvising.)
