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Tag Archives: Lerdahl

A not inconsiderable divergence from the original theory, but it certainly keeps things simple implementation-wise :)

Lerdahl, part 2

This is a sequel to this post on Lerdahl’s GTTM.

Okay…apologies for the delay…I was busy, but also was uncretain whether I understood the material myself, that stopped me from saying more. Additional disclaimer: I’ve tried my best to pull out all the melody and counterpoint related content of the theory to leave things chordal. I’ve savaged the original theory in the process. Apologies to all affected by my act of gross violence.

Prolongation Trees

Okay, so what is a prolongation tree? They look like this:


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First part of three.

Lerdahl, part 1

(serialized from this tigsource thread)

I couldn’t find any nice stuff on-line, but I’ve been meaning to properly go through this stuff myself for a while, so I’m happy to have the excuse to learn something about it (Disclaimer: all of what I’m saying is a filtered version of what Lerdahl says in his book, both through my misunderstandings, and my understandings of what might be useful to Muku in his PG music program (This is primarily a response to a request made by him for info on this stuff, but of course I’d love if other people were to chip in and comment)).

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Tigsource articles, that will appear here anyway, can be found here, if you can't wait for me to copy and paste them on here.

GTTM-based Chord Progression Generator

I’ll be posting some articles about the theory of Lerdahl very very soon. In anticipation of them (and to put something up so I can submit it to the Haskell Activity Report), here’s my implementation of a toy-model based roughly around his theory. It’s restricted to the process of chord generation.

Here‘s a simple playing by me of a chord-sequence that it produced. Here‘s a midi example that it produced by itself when I had it more developed.

There’s still a reasonable amount of work to be done on it, but it’s at a stage where it’s presentable.

Anyway, the current version of the haskell source code is here. Hopefully I’ll have more developed versions up in the future.