Anatomy of a Digital Musical Composition

For Dennis is the result of a recent conversation with a friend He described an idea he had for a musical composition memorializing the thousands of victims of the terrorist attacks on September 11, 2001. His description of the piece he had in mind was the inspiration for the following bit of Ruby code:

ruby

# Copyright 2024 Kirk Rader

# For Dennis

base_tempo = 60.0
total_ticks = 2606.0
adjustment = (2.0 * Math::PI) / total_ticks
volume = 0.5

define :adjust do |x|
  return 1 + (Math.cos( 4 * x * adjustment) / 2)
end

in_thread do
  beats1 = (spread 87, total_ticks)
  beats2 = (spread 60, total_ticks)
  beats3 = (spread 59, total_ticks)
  beats4 = (spread 125, total_ticks)
  beats5 = (spread 40, total_ticks)
  with_bpm base_tempo do
    total_ticks.times do
      tick
      synth :pretty_bell, note: 60, pan:  0.00, amp: volume
      synth :pretty_bell, note: 48, pan: -0.66, amp: volume, sustain: 20 if beats1[look]
      synth :pretty_bell, note: 54, pan: -0.33, amp: volume, sustain: 30 if beats2[look]
      synth :pretty_bell, note: 66, pan:  0.33, amp: volume, sustain: 29 if beats3[look]
      synth :pretty_bell, note: 42, pan:  0.66, amp: volume, sustain: 15 if beats4[look]
      synth :pretty_bell, note: 72, pan:  0.00, amp: volume, sustain: 25 if beats5[look]
      sleep adjust(look)
    end
  end
end

When executed by Sonic Pi, the output of the preceding 27 lines of code is the 44ish minutes of For Dennis.

My goal for this work was to produce music that is meditative rather than entertaining or emotionally rousing. It is entirely algorithmic in conception and execution. The only "artistic" choices made were the exact parameters for things like the pitch of each voice, the number of beats each voice is played over the course of the work, and so on.

In the spirit of my friend's original conception, I chose numbers which memorialize the victims of 9/11. The primary "heartbeat" is played exactly 2606 times, once for each person who died that day in the World Trade Center towers. The other voices are played a number of times each that corresponds to the victims in each of the hijacked planes and on the ground at the other affected locations. If you listen to the whole piece, by the end you will have heard one note played for each person murdered that day. In addition, the tempo speeds up and down subliminally at first, then quite noticeably, over the course of the piece in four waves, once for each hijacked plane and the people killed by each crash.

None of this is exactly what my friend described in his vision for such a piece. But I was definitely inspired by his ideas to create a work of my own that I hope is consonant with his intention.

Anatomy of a Digital Musical Composition ​

Anatomy of a Digital Musical Composition