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    Lesson 3. Defining Chords



    So this is how chords are made: by compressing pitches together!


    (setf chords '(c4cs4fs4 g4c5))


    There are ways of making chords from pitch lists using system functions like GEN-CHORD, but it’s a little easier for this example to simply write it out!


    (setf chord-lengths (span lengths chords))


    This expression isn’t strictly necessary as the rhythm is going to be the same for both hands of the piano. But try the Audition tool to hear the SPAN of the rhythm onto the chords: select the following code in the Composer panel and press ⌘1 to hear it.


    (setf piano-lefthand
           :length lengths
           :pitch chords
    => (e c4cs4fs4 mp g4c5 c4cs4fs4 g4c5 c4cs4fs4)


    Above is the output of the MAKE-OMN function bringing together the three parameters in a single line of script. Note the position of the parameters of length e, pitch c4cs4fs4 and velocity mp.


    If we’re not going to change the rhythm and the dynamics we don’t have to state them again for each pitch in the list. Finally, you may have notice in the notation that pitches c4 and cs4 don’t look comfortable together as a cluster. So try this and look at the result in notation with ⌘1.


    (setf chords (respell '(c4cs4fs4 g4c5)))


    (setf pitches '(c4 cs4 fs4 g4 c5))
    (setf transposed-pitches (pitch-transpose -24 pitches))
    (setf chords (respell '(c4cs4fs4 g4c5)))
    (setf lengths (span pitches '(e)))
    (setf chord-lengths (span lengths chords))
    (setf piano-righthand
           :length lengths
           :pitch chords
           :velocity '(mp)))
    (setf piano-lefthand
           :length lengths
           :pitch transposed-pitches
           :velocity '(f)))
    (setf timesigs (get-time-signature lengths))
    (def-score lesson-3
               (:key-signature 'chromatic
                :time-signature timesigs
                :tempo 100
                :layout (piano-layout 'piano-rh 'piano-lh))
       :omn piano-righthand
       :channel 1
       :sound 'gm
       :program 'acoustic-grand-piano)
       :omn piano-lefthand
       :channel 1)


    Screen Shot 2017-12-04 at 20.57.49.png

    Next page Lesson 4. Rhythm, Repeats and Random Seeds

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