Monday, March 14, 2011

Motivation

Today I was prompting my students to think of reasons why the subdominant chord (IV) is more common than the supertonic chord (II) as a predominant within the standard phrase model. As part of this, we talked about what motivates people in the creation of systems and languages. I was aiming at ease of use, pointing out that IV chords are the same quality as tonic chords, and therefore will be easy to play with the same hand shape for most chord-based instruments. But students also brought up the desire for stability brought about by redundancy of information. So the repeated chord quality will emphasize and stabilize the major or minor mode of the tonic more than the II chord. This redundancy is also seen in the tonic note shared between the tonic and subdominant chords.

But all of these stabilizing features also give the IV chord a less effective predominant function. The IV chord shares so much in common with the tonic chord (I) that it can easily move back to the tonic with no real disappointment of unrealized expectation. Thus it doesn't have as strong of a push to move to the dominant chord (V) as the II chord. Thus the choice of predominant is really a choice of motivation. Easiness and stability vs. tension and movement.

3 comments:

James said...

Hi Scott,

Interesting class discussion... Beside your "motivation" theory, there are obviously other factors such as melody harmonization (e.g. ^2 vs. ^1), stylistic differences (e.g. Baroque and jazz preferences for ii over IV), the relative value of descending fifth progressions (thus favouring ii), and the union of ii and IV with the ii6/5 chord. Functional ideas from Riemann and Rameau might be germane here too (though not usually covered in this pedagogical context). Obviously you can't cover everything in an undergrad class. But the cool thing about your approach using "motivation" is that you can use that as a "way in" to several more advanced concepts engaging the students along the way. Nice work, Scott.

Allen H Simon said...

Maybe you covered this elsewhere, but how do you know the IV chord is more common as predominant than ii ? My subjective observation is that in the Baroque and Classical periods, at least, that the ii chord (usually in first inversion) is more common. Is there some research about this?

Scott said...

Allen, I don't know for sure. There has been some research on the statistics of chord use, but I don't know that it has been tied with function as much as just Roman Numeral usage. I posed the pseudo fact more to make the students confront their own thoughts about supertonic and subdominant chords.