Voice Leading: Control Through Counterpoint (Part 2: Voice Independence)
Intro:
Last week we covered the basics of controlling dissonance between voices, but there's a lot more to (good) void leading. Today we'll be looking at voice independence which is what really gives older styles of music their distinct sound and complexity. The concept of voice leading is simple enough. Keep voices sounding distinct from one another in their own range, or occasionally crossing each other. However, in practice it's a topic that can cause a lot of heart ache for theory students because, at least in the beginning, there are a lot of rules that must be followed. A lot of these rules become guidelines later on, especially in the cases such as doubling, hocket, octave displacement, etc. That being said, the goal here isn't necessarily to follow strict voice leading rules, but to work towards some best practices.
What is Voice Independence, Really?:
Voice independence refers to a set of rules about how voices and intervals should be treated so that two or more voices always sound distinct to the listener. These rules were especially important in religious choral music where clarity of the text was a priority over the music itself. Most of the rules had to do with preventing parallel movement such as unisons, octaves, P4, and P5 as they would generally lead to upper voices being indistinguishable from the overtones of the lower voice. Between two voices this is relatively simple, but as we add more voices we'll start running into complications involving range. More on that later.
Going back to the previous exercise, if you spent time playing around with different solutions you may have already heard differences between when the voices are moving in parallel versus moving in opposite directions. While a reliable solution may be to always make sure the two voices are mirroring each other this isn't necessarily interesting or musical. Also, just because we're avoiding some parallel movement doesn't mean we're avoiding all parallel movement. Before going any further let's define a few terms regarding the types of movement.
Contrary Movement - movement in opposite directions by either steps or leaps
Oblique Movement - one voice moves up or down while another voice stays on the same note
Parallel Movement - generically referring to any movement where the interval between the voices remains the same
Hidden Parallels (4ths, 5ths, Octaves) - when two voices move in opposite directions, especially leaps, arriving at an interval of a 4th, 5th, or octave
Contrary Movement:
Contrary movement will always be correct as it naturally avoids (non hidden) parallel movement, and generally avoids range issues. That becomes less reliable when you start writing bass voices that do more leaping than steps, and you start to run into the hidden parallel foot gun (which has resulted in a lot of red ink flowing on the pages of student work). Another problem is that it's not particularly interesting to listen to music where the voices only ever mirror each other. Despite all the rules, the main goal is to make music that is interesting to listen to and perform. Contrary movement is generally more useful for writing counter leads/melodies where you already have an established melody, and need to write a part for a slightly lower voice.
Oblique Movement:
While drones are generally considered a function of bass/lower voices they can be incredibly useful in upper voices. Oblique movement is especially useful in inner voices when there isn't a lot of room to move, and creates a nice effect in cadences where the voice may already be on the root; simply stays there while the other voices move in the last beat/measure. You do have to be careful as it can create situations where a voice will spend a long time on a single note, or you can end up needing to move with options being limited to parallel movement.
Parallel Movement:
Parallel movement is tricky in that it's only mostly forbidden, and other times okay depending on the interval between the notes and which voices are involved. In the cases of unisons, octaves, fifths, and fourths it's definitely something to always be avoided. However, when involving inner voices you can get away with parallel thirds and sixths. You can technically have these parallels between the lowest and highest voices without problems, but it's best to avoid all parallel movement between these voices when possible.
Hidden Parallel:
Really, any time two voices leap to the same note in different octaves it's considered parallel movement because the exact octave/pitch of the note isn't considered as part of the analysis since all notes are evenly tempered (A3 to C3 is treated as the same interval-- m3-- as A3 to C4). That being said, unisons, octaves, fourths, and fifths are the forbidden cases as they will cause voices to mask each other.
Conclusion:
Currently we're still only focusing on two voices, and how to control dissonance and maintain voice independence. I encourage you to go back to the exercise from last week's blog, and try to implement some of these concepts. It doesn't have to be done perfectly for our purposes, but well enough to understand the concepts on your own. Unfortunately, I don't have a way to check people's work, but I am considering doing some YouTube demonstrations to link to these blog posts in the future. It will also help to keep from having to liter these blogs with images and gifs. After all, these blog posts are meant to communicate the concepts, it's still up to the reader to do some exploration on their own to really reach a level of mastery.
