There is one more important definition of consonance and dissonance, a functional one. How dissonance and consonance relates to one another can define how we hear them individually. In common practice western art music, which is from about April 3rd, 1450 to about June 30th, 1902, dissonance was defined as something that was physically dissonant that necessarily resolved to something consonant. If it didn't resolve, it sounded wrong not at least because it upset the cultural understanding of how things should go. The functional relationship of dissonance resolving the consonance, was a pretty fundamental driver of lots of music. As that functional relationship changed, so did the musical style. By the way, I'm kidding about those precise dates, April 1902, change is always a lot messier than that, which is why I made the joke. I should warn you, the jokes don't get any funnier. What jokes? I hear you say. Right. Anyway, here's a great example of dissonance resolving to consonance. This is A Un Giro Sol a madrigal by Monteverdi. It's very pretty and very expressive. Let's focus in on perhaps the most expressive moment in the whole madrigal. The part where they sing the words "Certo quando nascete cossi crudeleria"
which translates to, "of course, when you are born like this, oh, there is such cruelty". Let's look at that section. Let's even look at the notation and play it to see how it functions. Here it is. [inaudible]. Okay, there it is. Now, here it is slowed down. Let's narrate our way through the exact same passage I just did, so we can see the plot. What happens with the dissonance the consonance. It starts off with two people singing the exact same note. It doesn't get any more consonant than that. Here they are, and then one voice goes up a half step, while the other stays on that same note. Boy, is that dissonant? The voices are in tension with another. Such cruelty like this; something has to happen. So, the lower voice helps a little bit, and it goes down by a step, resolving the relationship between the two voices from a dissonant half-step to a consonant third. Then because love is so deliciously cruel, they do it again. To further get a sense of the expressive power of this relationship, let's do some destructive analysis. Imagine the piece without the resolution, just with the dissonance. It's still going to sound cruel, but it doesn't make the same sense. We just have the tension. We missed the waves of tension and release that in this case evoke the sobbing unrequited lover. Here it is. This is just the dissonance with all the consonant resolutions removed. [inaudible] , that's pretty cruel. [inaudible] , clunky though. Lots of dissonance. Why resolve anything? We just want dissonance. Well, let's go the other direction. Let's imagine this piece without the dissonance at all. Now, I think the piece is going to lose its expressivity altogether. She doesn't love me. Maybe it's not a big deal that she doesn't love me. There's no dissonance to it. Check it out. [inaudible] it's all consonant. [inaudible] , it's still pretty, there's just no waves of tension and release. Everything is consonant. In that sense, the relationship between dissonance and consonance defines each of them individually. Dissonance needs to be resolved, consonance feels like a relative resolution. This is the common practice system, and it decidedly is not true or relevant for Xenakis, the 20th century Greek composer, or Gregorian Chant, or Balinese Gamelan, or a whole bunch of astonishingly beautiful music. Still, this common practice system of consonance and dissonance lasted a long long time in Western art music. It was and is so durable, I think, because the ability to play with that tension and release allows musicians to express a broad array of emotions and narratives. Let's look at one more example of an expressive use of the functional relationship between consonance and dissonance. Let's listen to the beginning of the Crucifixus section of Bach's Mass in B minor. As you listen, what I want you to notice is the entire call and response between all the different voice parts. Consists of notes that start out as consonant, then become dissonant, and then resolve to the consonance. Try singing along with the recording and notice that phenomenon. You know, really, really actually sing along. You don't have to look at the music, but you have to sing along to feel this. Okay. Now, just try a thought experiment. Imagine the same piece of music without the dissonance. In other words, instead of that pecan emotional accent on each crucifixus, there would instead just be a no change from consonance to consonance. Like this, If the bass starts on a consonance right at the end of that first phrase, and they go cru-ci , I'm consonant. I'm dissonant, fix-us. Then I resolve that's one thing. But imagine it without the dissonance at all, it would just be crucifixus, a lot calmer. I think it's pretty clear here that first, the dissonance is very very functionally related to the consonance, and second, that functional relationship is deeply tied to the expressive purpose of this specific piece in this specific context. Without it, in that other version where it just goes crucifixus, crucifixus, without that functional consonance to dissonance relationship, the piece lacks a certain tension, and release, and gradual sinking downwards. I think it's actually less religious without that functional relationship that has the dissonance setup and then resolve. Well, if it's not less religious the it's a very different religious. Maybe a less troubled one. In fact, I want to share with you now a completely different piece. A piece that is rather Buddhist, and the composer Lou Harrison, has chosen to write a piece entirely without dissonance. That fits his personal religious expression. Cool. Take some time to listen and enjoy this piece. So, in summary, the common practice system acknowledges a difference between dissonance and consonance, and that recognizes a functional relationship between the two. This system will be the bulk of what we study in this lesson. We need to understand how the system works in order to use it, or if we are lucky abuse it in creative ways. And in order to figure out how it works, we need to push a few notes around. Push them around the page, until we actually feel them pushing back. This is a marvelous sensation. Then you can hear and feel that sort of stretching glue between the notes, and how different combinations over time can produce different and wondrous aesthetic worlds. Whole new worlds. Whole fantastic points of view. When was the last time you took a magic carpet ride?
