dave yarwood
Out of the Blue


July 15, 2019


In January 2019, I collaborated with the choreographer Renay Aumiller to create a modern dance piece called Out of the Blue. I wrote a program that prompted the audience to contribute a list of body parts and dance qualities, and then fed that creative input into an algorithm to randomly generate a series of short dance vignettes.

Each vignette featured a body part and a movement idea contributed by the audience, as well as a short piece of music to accompany the music. Renay improvised modern dance movement on top of this, to sometimes poignant or comedic effect.

I composed the musical backdrops in Alda and my program cross-faded them dynamically based on the randomly generated length of each vignette (30-90 seconds). For this recorded version, each backdrop is played for 30 seconds before cross-fading into the next.

Here is the Alda source code for each backdrop, accompanied by some notes about my creative process. Hopefully you’ll find it interesting!

I employed a little trick to inspire myself as I was composing most of these musical scenes. I wrote a program that picked 2 or 3 instruments at random and played randomly chosen notes on those instruments. The results weren’t usable out-of-the-box, but every few runs of the program, an interesting combination of instruments would occur by accident, and that inspired me to see what interesting musical ideas I could come up with using those instruments.


Backdrop #1 is super simple, just a long, low G on strings, punctuated regularly with timpani hits. I think it has on overall feeling of “medieval suspense”. I thought this was interesting enough as-is, and moved onto the next backdrop.

(tempo! 85)

md = (vol 80)
lg = (vol 100)

  (panning 90)
  o2 md g8 %downbeat [ lg g2.. o1 md g8 lg g2.. o2 md g8 ]*99

  (panning 10)
  (volume 60)
  (quant 99)
  o1 @downbeat g1~1~1~1 *99


For Backdrop #2, I took the output of one of the runs of my score generator program and I used it almost as-is.

The generator emitted two instrument parts, a kalimba and a music box. I played up the percussive sound of the kalimba by creating an artificial delay effect; I added three more kalimbas and had them play the same notes, spaced apart from one another in 250ms intervals, and added progressive levels of panning and volume decay. I think it kind of sounds like a ping-pong ball falling down the stairs into the basement.

(key-sig! [:e :flat :locrian])

kphrase = o2 f2397ms o3 d2598ms o3 d2638ms o3 g1949ms
mbphrase = o2 e875ms o2 e1044ms o2 c2667ms o3 e2939ms o1 e659ms

midi-kalimba "mk1":
  (panning 50)
  kphrase * 100

midi-kalimba "mk2":
  (panning 60) (vol 75)
  kphrase * 100

midi-kalimba "mk3":
  (panning 70) (vol 50)
  kphrase * 100

midi-kalimba "mk4":
  (panning 80) (vol 25)
  kphrase * 100

  (panning 6)
  mbphrase * 100


My generator happened to pick a MIDI ocean wave sound (the General MIDI spec includes a number of other goofy sounds like a gunshot, a telephone ringing, etc.), so I composed something simple and relaxing to accompany the sound of the waves.

A celeste outlining an A minor pentatonic cluster (A - C - D - E - G) seemed to do the trick. I had the celeste wait 10 seconds, then play the same thing, shifted down a note within the context of A minor (G - B - C - D - F). Then I just kept doing that, working my way down the scale. Boom, backdrop done. Next!

  (vol 70) (pan 20)
  o0 c150s

  (tempo 100)
  (vol 50) (pan 95)
    r10s o4 a8 > c   d   e   g2.
    r10s o4 g8   b > c   d   f2.
    r10s o4 f8   a   b > c   e2.
    r10s o4 e8   g   a   b > d2.
    r10s o4 d8   f   g   a > c2.
    r10s o4 c8   e   f   g   b2.


The inspiration generator gave me a helicopter sound and pizzicato strings next. Challenge accepted! I wrote some inline Clojure code to generate sequences of D notes moving up in octaves (D1, D2, D3, D4, D5), separated by random-length pauses. I think the result sounds like the score to a movie scene where a spy is infiltrating a military base or something.

(defn random-pause
  (pause (duration (ms (rand-nth (range 300 4000))))))

(defn pizz-sequence
  (for [octave-number (range 1 5)]
    [(octave octave-number)
     (note (pitch :d) (duration (ms 1000)))

(defn heli-sequence
   (note (pitch :c) (duration (ms (rand-nth (range 3000 10000)))))])

  (pan 30)
  (repeatedly 99 pizz-sequence)

  (pan 100) (vol 50)
  o0 (repeatedly 99 heli-sequence)


For Backdrop #5, I imagined that I was playing some simple arpeggios on a clean electric guitar. I think GM instrument #101 (“FX 5 (brightness)”) is intended to be played in a higher register, but it ended up sounding pretty neat as a bass, sort of like a more electronic-sounding bowed upright bass.

(tempo! 90)

  (quant 400)
  (pan 0)
  (vol 75)
    o3 [ c8   e g   b > e < b   g e ]*4
    o2 [ a8 > e g   b > e < b   g e < ]*4
    o3 [ c8   f g > c   e   c < g f ]*4

    o2 c1~1~1~1
    o1 a1~1~1~1
    o1 f1~1~1~1


I think I must have been channeling VGM composer Nobuo Uematsu when I wrote Backdrop #6.

It’s always fun to play with changing chords while keeping the bass note the same. In this case, the bass guitar plays a steady stream of B quarter notes, while the electric piano plays a different chord every 4 measures (Bm7 - G7 - Cmaj7 - Bm7).

  (pan 10) (vol 70)

    r1 *4

    [ o6 g16 d < b g f+ d < b   g   f+2 | r1 ]*2
    [ o6 g16 d < b g f  d < b   g   f2  | r1 ]*2
    [ o6 e16 c < b g e  d   c < b   g2  | r1 ]*2
    [ o6 d16 c < b g f+ d < b   f+  d2  | r1 ]*2

  (pan 90) (vol 60)
  (quant 150)

    r1 *4

    [ r1 o3 b1/>d/f+/a ]*2
    [ r1 o3 b1/>d/f/g ]*2
    [ r1 o3 b1/>c/e/g ]*2
    [ r1 o3 a1/b/>d/f+ ]*2

  o1 b4 *999

  o2 c4 *999


This backdrop starts with a piano alternating between Gmaj7 and Dmaj7. I added a second piano that plays exactly the same thing, but softer and panned differently, creating a nice echo effect, as if you’re standing in a cathedral and the sound from the piano is bouncing off of the back of the room.

The chord voicings I chose happened to have 5 notes in them, so I thought it would be interesting to arpeggiate the chords from top to bottom in quintuplets. This has an especially dreamy effect with the artificial echo.

(tempo! 150)

pianoPart1 = [
  (quant 90)
    [ o2 g4/>d/g/b/>f+ ] *16
    [ o2 d4/a/>d/f+/>c+ ] *16

pianoPart2 = [
  (quant 400)
    {o4 f+ < b g d < g}2 *8
    {o4 c+ < f+ d < a d}2 *8

pianoPart = [ pianoPart1 pianoPart2 ]*20

midi-electric-grand-piano "echo":
  (vol 80) (pan 25)

midi-bright-acoustic-piano "main":
  (vol 50) (pan 100)
  r8 pianoPart

  (quant 100)
    # pianoPart1 unaccompanied
    r1~1~1~1 *4

    # pianoPart1 with this accompaniment
      [ o1 g2.. > d8 a1 ]*2
      [ o1 d2.. > f+8 > c+1 ]*2

    # pianoPart2 unaccompanied
    r1~1~1~1 *4
  ]* 20


Backdrop #8 is conceptually simple, but fun to listen to. There are 8 voices, each playing a randomly generated sequence of pizzicato notes with random-length pauses. It starts with only one voice doing this, and then every 10 seconds a new voice enters. The result is that over time, the music becomes progressively more dense and chaotic, like the sound of popcorn popping in the microwave.

(key-sig! [:e :major])

(defn random-notes
  (for [n (range 1000)]
    [(pause (duration (ms (rand-int 500))))
     (octave (rand-nth (range 2 6)))
     (note (pitch (rand-nth [:e :g :b :d]))
           (duration (ms (rand-int 2000))))]))

  V1: (pan 15) (random-notes)
  V2: (pan 90) r10s (random-notes)
  V3: (pan 30) r20s (random-notes)
  V4: (pan 75) r30s (random-notes)
  V5: (pan 45) r40s (random-notes)
  V6: (pan 60) r50s (random-notes)
  V7: (pan 25) r60s (random-notes)
  V8: (pan 80) r70s (random-notes)
  V9: (pan 50) r80s (random-notes)