Video 7d: Partwise vs. Timewise Polyphonic Representations

Key Takeaways

hello as the last element in our discussion of musical representations I want to talk about two different fundamental ways that we can represent musical scores TimeWise and partwise and these really matter in anything that has more than one note or more than one independ part going s once and I want to acknowledge I'm going to be using slides from a presentation called notation as composition by William Andrew burnson creator of the B bage notation package one of the ways that we can look at musical notes is as musical scores is as a series of containers so that we can think of uh and part based containers so we have a score and within that score as the first element we have two parts in this case and within those parts we have measures and we might even go further and think that within those measures we have voices but first when we think about dividing a score into parts let's say it's you know the score of um a massive three-hour Opera well you start with you whatever's at the top of the piccolo or something like that and you go with the piccolo part from measure one all the way to the end of the three hours then you go to the second part probably the flute and you go all the way from one to the end and so on and so you have everything in one part from the beginning to the end and it makes it very easy to do the kinds of analysis that look at what happens in the part the other principal way of looking at musical notation representation is you have a score and within that you have all the things that happen at a certain moment so that be getting you know you might say well there's all the clubs and if it's a 10 bar score you might have trouble trouble trouble trouble trouble Alto base base Bas base Bas so on and then you have all the time signature key signatures all the time signatures and then every note everything that happens at the beginning of the piece and then you have everything that happens at the next instant the next time that something happens here and in this particular case when we get to the third instant um which is the E quarter note in the base and then the c u the C eighth note in the E there there is something that's happening in the top part that that g half note that is not represented in that instant but is thought to be continuing from before and in the next instant the there was just a an eighth note with nothing else happening and so this makes it very nice to see what's happening at every attack and you might be able to programmatically go back and see what's happening at every instant but it makes it very hard instead to figure out what's happening from one uh beginning of the score to the End by the way we call these instance uh instance or uh offset moments or you know cuts through hierarchies generally speaking but often we Cally call these salami slices in the process of creating these things salami slicing it's just kind of something that's come out in music 21 we call this process codification and so you'll see the cify happens a lot so which is better part-based containers or time based containers each of these formats has their own POS positive things and drawbacks as I said part-based containers make it very easy for us to follow an entire part from beginning to end an entire line from beginning to end time based containers let us see what chords are happening in a certain moment but very hard to follow Melody but each of them has certain uh certain difficult to encode things for instance in alia staff uh a staff where something uh optional is happening or or you can do this instead of something else what part is that in how do you encode that uh do you put a part with hidden measures all the way up to this moment and hidden measures all the way to the end and how do we indicate that the player could do this so this is something that's very hard to encode when we do part-based representations so instead let's move to time based representations because it doesn't have this they don't have this problem but instead they have other problems where do we put these Grace notes uh in you know in in encoding like this especially when you know we know that not all five of those Grace notes come after that last let's assum it's trouble in base Club after that last B of the sub tuplet within the triplet you know where do we go how do we encode Grace notes do they attach to the note next to them or or what and both of the representations have maj problems when we want to look at things that involve horizontal and vertical at the same time things like voice leading here's a common uh voice leading error in uh in sort of very strict traditional uh harmonic writing where we have um and we have a overlap where the low G crosses the boundary established by the B before and goes up to the C above it which form format makes this possible to see if you're just look at each part alone you see okay there's a b going to an E then we get to the next part there's a g going to a c but you don't see that the G Going to the C overlap the B going to an e on the other hand if we look at it in time based we have a g and a b and we look at that then the next part we see there's a c and an e but it's hard to tell well did the G go to the C did the G go to the E did the you what what happened how's the voice leading happen so these are the problems in musical representations and we'll quite often find that we have to convert from part-based representation to time based representation and back or in the case of a voice leading moment we have to keep both the part and the time based representations in in our head in the musical memory in the representation at the same time in order to find these things I find these problems really cool and hope you guys do too and solving them is is another one of the great choice of this class