• Lesson 12. Pitch Variation and Articulation

Annotation

This piece in A B A structure sets side-by-side two different ways of generating pitch material for the right hand.

The first we’ve met before:

```(setf line-rnd (gen-eval 5 '(rnd-sample (rnd-range 3 5) line) :seed 41))
=> ((g4 cs4 c5 cs4) (fs4 c5 fs4 cs4) (c5 g4 g4 fs4 c4)
(fs4 c5 g4 c5) (c4 c4 cs4))```

The second is using a generation function able to produce Markov chains.

```(setf line-rd (rnd-sample (length (flatten line-rnd)) line :seed 35))
=> (fs4 c5 fs4 cs4 c4 c5 c5 g4 g4 fs4 c4
c5 c5 fs4 c4 fs4 c5 c4 cs4 c4)```

GEN-MARKOV takes the output of randomizing our scale line and reorders it to highlight the inner patterns of line-rnd.

```(setf line-markov (encode-seq (gen-markov line-rd :seed 35)))
=> (c4 c5 c5 g4 fs4 c5 fs4 c4 c5 c5 g4
fs4 c5 fs4 c4 fs4 c4 cs4 c4 cs4)```

We need to match the line-rnd with line-markov. Although we could simple count the number of pitches in line-rnd it’s more accurate, and certainly quicker and easier in a larger list, to use GET-COUNT

```(get-count line-rnd :sum t)
=> 20```

This piece features the use of articulation to enhance section B:

`(setf no-artic (gen-repeat 5 (list '(-)))) `

'(-) this means no articulation, or:

`=> ((-) (-) (-) (-) (-))`
```(setq staccato (gen-repeat 5 (list '(stacc))))
=> ((stacc) (stacc) (stacc) (stacc) (stacc))

(setf articulations-ABA (append no-artic staccato no-artic))
=> ((-) (-) (-) (-) (-)
(stacc) (stacc) (stacc) (stacc) (stacc)
(-) (-) (-) (-) (-))```

When made into an OMN list with MAKE-OMN the articulation looks like this:

```((e g4 f cs4 c5 cs4) (e fs4 p c5 fs4 cs4)
(e c5 f g4 g4 fs4 c4) (e fs4 p c5 g4 c5)
(e c4 ff c4 cs4) (e c4 p stacc c5 stacc c5 stacc g4 stacc)
(e fs4 mp stacc c5 stacc fs4 stacc c4 stacc)
(e c5 p stacc c5 stacc g4 stacc fs4 stacc c5 stacc)
(e fs4 mp stacc c4 stacc fs4 stacc c4 stacc)
(e cs4 mf stacc c4 stacc cs4 stacc) (e g4 f cs4 c5 cs4)
(e fs4 p c5 fs4 cs4) (e c5 f g4 g4 fs4 c4)
(e fs4 p c5 g4 c5) (e c4 ff c4 cs4))```

Remember, by just repeating the articulation stacc the note-length, pitch and dynamic are automatically repeated, as above.

Score

```(setf line '(c4 cs4 fs4 g4 c5))
(setf bass (pitch-transpose -24 line))
(setf line-rnd (gen-eval 5 '(rnd-sample (rnd-range 3 5) line) :seed 41))
(setf line-rd (rnd-sample (get-count line-rnd :sum t) line :seed 35))
(setf line-markov (gen-markov line-rd :seed 35))
(setf line-markov-d (span line-rnd line-markov))

(setf bass-line (span line-rnd bass))
(setf bass-markov (pitch-transpose -18 (span line-markov-d line-rnd)))
(setf bass-select (filter-first 1 bass-line))
(setf bass-markov (filter-first 1 bass-markov))

(setf rhythm (span line-rnd '(e)))
(setf bass-rhythm (gen-repeat 3 (mclist (get-span rhythm))))

(setf dynamics (mclist '(f p f p ff)))
(setf dyn-spanned (span line-rnd dynamics))
(setf dyn-markov (mclist '(p mp p mp mf)))
(setf dyn-markov-spanned (span line-markov-d dyn-markov))

(setf ABA-rh (assemble-seq
line-rnd
line-markov-d
line-rnd))

(setf ABA-lh (assemble-seq
bass-select
bass-markov
bass-select))

(setf rhyABA (assemble-seq (gen-repeat 3 rhythm)))
(setf rhyABAb bass-rhythm)

(setf dynABA (assemble-seq
dyn-spanned
dyn-markov-spanned
dyn-spanned))

(setf no-artic (gen-repeat 5 (list '(-))))
(setq staccato (gen-repeat 5 (list '(stacc))))
(setf articulations-ABA (assemble-seq no-artic staccato no-artic))

(setf line-1 (make-omn
:length rhyABA
:pitch ABA-rh
:velocity dynABA
:articulation articulations-ABA))

(setf bass-1 (make-omn
:length rhyABAb
:pitch ABA-lh
:velocity dynABA))

(setf ts-list (get-time-signature line-1))

(def-score lesson-12
(:key-signature 'chromatic
:time-signature ts-list
:tempo 100
:layout (piano-layout 'piano-rh 'piano-lh))

(piano-rh
:omn line-1
:channel 1
:sound 'gm
:program 'acoustic-grand-piano)

(piano-lh
:omn bass-1)
)```

Notation

Go back to Reference page.

Edited by opmo

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