In this activity, we will create a simple electronic music track using the Sonic Pi programming environment.

1. Setup

If you are using a Raspian-based computer (PC or Raspberry Pi), you should already have Sonic Pi installed on the computer.

If you need to download Sonic Pi, go to https://sonic-pi.net/ and choose the correct version to download.

2. First Sounds

Sonic Pi is a programming language designed to play electronic music. It runs within an Integrated Development Environment that lets you type code and run it with a few key presses.

When you open Sonic Pi, you should see something like this: .

You will write your code on the left. You can run and stop your code using the menu buttons, or by using key shortcuts (Alt-R to run, Alt-S to stop).

To test this out, we’ll play a drum sample. Write the following code and run it:

 sample :bd_haus

When you run this code, you should hear a bass drum sound. It will only play once, so if you want to hear it again, you will need to run the program again.

Try some different drum sounds. If you start typing sample :bd then you should see an autocomplete menu with some other examples. Try changing the sample and run the program again.

3. Loops

The most interesting part of Sonic Pi is the ability to create live loops that will keep playing until they are stopped. Delete the code you have, and replace it with the following:

use_bpm 60

live_loop :kick do
  sample :bd_haus, rate: 1
  sleep 0.5
end

We set the bpm (beats per minute) to 60, which means we get one beat every second. We then create a loop called kick that plays our sample. It then sleeps for half a beat, which means we get two kick drum samples played per second.

Try changing the rate and sleep values to see what happens.

4. Drum beat

A typical drum beat has a kick drum, snare drum and hi-hat cymbal. We’ll add these in. Change your kick drum loop so it looks the same as in the previous section, then add the following code for the snare and hi-hat:

live_loop :snare do
  sleep 0.5
  sample :sn_dolf
  sleep 0.5
end

live_loop :hihat do
  sample :drum_cymbal_closed
  sleep 0.25
end

5. Bass

So far we have just played samples of drums and cymbals. Now we will add in an electronic instrument called a Synthesizer to make a nice bass sound. We will only make it play one note. Add the following code to your current program:

live_loop :bass do
  use_synth :prophet
  play :E1, release: 3
  sleep 2
end

Our instrument is an emulation of a famous synthesizer called the Prophet-5. We make it play an E1 note. We then sleep for two beats. Try changing the release value to see what happens.

6. Arpeggios

This isn’t a very interesting song so far, so we’ll add in some more synthesizer sounds that are playing random beep sounds. To make things more interesting, we’ll play random notes from a music scale (E minor).

Add the following code to your program:

live_loop :bleep do
  use_random_seed 123
  4.times do |i|
    16.times do
      use_synth :beep
      play chord(:E3, :minor).choose, attack: 0, release: 0.1, cutoff: rrand_i(50, 90) + i * 10
      sleep 0.125
    end
  end
end

Try changing the random_seed number and see what happens.

7. Chords

To finish our program, we’ll play some chords from the same E minor scale that we used earlier. Add the following code to your program:

live_loop :chords do
  use_synth :blade
  [1, 3, 6, 4].each do |d|
    (range -2, 2).each do |i|
      play_chord (chord_degree d, :e, :minor, 3, invert: i)
      sleep 2
    end
  end
end

This code is quite complicated, but it:

• Uses the blade synth sound
• Plays through the 1st, 3rd, 6th and 4th chords in the E minor scale in turn (Em, G, C, Am)
• For each chord, it plays four different inversions, moving up in pitch with each one.

Challenges

• Try changing each sample or synth sound
• Try changing the attack, release or other values of each sound
• Try adding effects (FX) to the sounds. You can click the Help menu button to see how to do this, and many other capabilities of Sonic Pi.
• Try live coding an entire song! As an example, you could watch the creator of Sonic Pi here: https://youtu.be/G1m0aX9Lpts

Full code listing

use_bpm 60

live_loop :kick do
  sample :bd_haus, rate: 1
  sleep 0.5
end

live_loop :snare do
  sleep 0.5
  sample :sn_dolf
  sleep 0.5
end

live_loop :hihat do
  sample :drum_cymbal_closed
  sleep 0.25
end

live_loop :bass do
  use_synth :prophet
  play :E1, release: 3
  sleep 2
end

live_loop :bleep do
  use_random_seed 123
  4.times do |i|
    16.times do
      use_synth :beep
      play chord(:E3, :minor).choose, attack: 0, release: 0.1, cutoff: rrand_i(50, 90) + i * 10
      sleep 0.125
    end
  end
end

live_loop :chords do
  use_synth :blade
  [1, 3, 6, 4].each do |d|
    (range -2, 2).each do |i|
      play_chord (chord_degree d, :e, :minor, 3, invert: i)
      sleep 2
    end
  end
end