Composing a piece using the idea of Dual Modality

Question

I've recently been studying a few early 20th century techniques and I would like to learn more about the concept of dual modality. I've read as much as I could find on the on the topic, but the only information I can find out about it is that you write two or more parts that typically have the same tonic, but use different modes. I've been listening to pieces from Béla Bartók's Mikrokosmos as examples in the topic to help me understand it better. What should someone keep in mind while composing a piece using the concept of dual modality?

Here is a small excerpt on the topic from the book from my composition class:

Answer 1

Great question Dom. I think your best bet is to make sure that the two modes are distinct and separate. This is achieved through rhythmic decisions, register, counterpoint, instrumentation, and a number of other musical factors.

If the lines containing the modes cross, the definition of each line becomes obscured, and therefore the harmonic contrast you've setup begins to degrade.

Looking at the Bartok, notice how he supports vertical intervals. Even though he's mixing modes, the intervals between the notes largely remain consonant. In fact, in the example you've provided, every 1st species occurrence (with the notable exception of the beginning and a brief repose in m.2,) is an imperfect consonant interval - a hallmark of interesting and appropriately supported counterpoint.

I mention this because here Bartok uses support through proper counterpoint to provide stability that is being offset by the dual modality.

Extrapolating this thinking further, you can explore for yourself how to negotiate each element of music appropriately for the sounds you're looking for.

Hope that helps.

Answer 2

After writing a short piece using this idea I would like to highlight a few points that I found to be kind of unique.

Choosing the Modes

Since the technique uses two different modes picking them and noting the similarities and differences between them. Picking two modes that are very close in what notes they use kind of defeats the purpose of this technique.

In my piece I decided to use the Lydian and Phrygian mode. Between these two modes, all 12 notes are used, but there are only two notes it common the root and the 5th. Because of this though, I had to be extremely careful with what notes were

Introducing the Modes

The two modes being used are at the heart of this techniques and thus it is vital to make sure that each voice has the mode it's using has to be established. A simple monophonic motive in each voice to highlight the mode was extremely useful.

Use of Imitation

To bring out the difference between the two modes playing one motive in one voice and then repeating it in the other helped highlight the differences between the two modes.

Use of "Dual" Haromny

There were many times that I would introduce duality in harmony. One simple example is for one beat the two voices would line up to make a I chord, but then with a voice exchange the chord would change into a i chord highlighting the difference in a very interesting fashion.

Cadences

Cadences were at times tricky since the harmony didn't always allow typical cadences. With the Lydian and Phygian modes I found the Lydian voice using the leading tone and the Phygian voice using the mode to use the supertonic to approach the tonic. Other mode combinations may yield various odd cadences.