We are going to investigate drum beats and learn a little programming. If you don't have Sonic Pi installed, you'll need to have that done.
Paste the following code into one of the Sonic Pi workspaces, and click Run.
# Drum loop one, half notes beat_length = 0.25 4.times do sample :drum_heavy_kick sleep beat_length sample :drum_snare_hard sleep beat_length end
This is a basic drum loop. Let’s look at the parts of the code line by line.
- The # symbol means that anything on the rest of the line is a comment. It’s for humans to read, the computer ignores it.
- We’ve made a variable named beat_length that means a value of 0.25. We’ll use this a few times later.
- This line is blank so we know that there is something different coming next.
- Here we are creating a loop that will do something four times.
- This plays a sample (recording) of a kick drum.
- The command sleep means to rest for a certain amount of time (in seconds). It will rest for the time stored in the variable beat_length.
- Play a different sample, this time a snare drum.
- This tells the computer that it is the end of the loop that started on line 4.
Now lets try adding a few things to the code to make it look like this:
# Drum loop two, quarter notes beat_length = 0.5 4.times do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length end
When you click Run you’ll hear high hat cymbal playing at the same time as the kick and snare drums.
Bars of music often have four beats in them, so let’s change it to this and it will play four bars with four beats in each:
# Drum loop three, quarter notes beat_length = 0.5 4.times do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length end
Now try changing the value in the beat_length variable to 0.25 or 0.7, and try replacing some of those samples with different drum samples:
sample :drum_heavy_kick
sample :drum_tom_mid_soft
sample :drum_tom_mid_hard
sample :drum_tom_lo_soft
sample :drum_tom_lo_hard
sample :drum_tom_hi_soft
sample :drum_tom_hi_hard
sample :drum_splash_soft
sample :drum_splash_hard
sample :drum_snare_soft
sample :drum_snare_hard
sample :drum_cymbal_soft
sample :drum_cymbal_hard
sample :drum_cymbal_open
sample :drum_cymbal_closed
sample :drum_cymbal_pedal
sample :drum_bass_soft
sample :drum_bass_hard
Cool, eh.
Next we’ll try some different rhythms by playing some samples halfway between beats. If each beat before was a quarter note, these would be eighth notes (because half of a quarter is an eighth). Listen to the kick drum:
# Drum loop four, quarter and eighth notes beat_length = 0.5 4.times do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length/2 sample :drum_heavy_kick sleep beat_length/2 sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length end
That seems to be getting a little long, though, let’s try the same thing with a loop:
# Drum loop five, another loop beat_length = 0.5 4.times do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open 2.times do sleep beat_length/2 sample :drum_heavy_kick end sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length end
Not much shorter, but hopefully you get the idea. We two spaces at the beginnings of lines 11 and 12 to show that they belong to a different loop. The computer ignores the spaces, but it makes it easier for other people to read your code. If you want to learn more about code style in this language, check out the Ruby Style Guide.
Getting back to loops, though, try this:
# Drum loop six, another loop beat_length = 0.5 4.times do 3.times do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length end sample :drum_snare_hard sample :drum_cymbal_open sleep beat_length end
You can see that on the first three beats we played the same samples, then different samples on the fourth beat.
Now let’s try some functions.
# Drum loop seven, with functions beat_length = 0.5 def kickAndClosed sample :drum_heavy_kick sample :drum_cymbal_closed end def kickAndOpen sample :drum_heavy_kick sample :drum_cymbal_open end 4.times do 3.times do kickAndClosed sleep beat_length end kickAndOpen sleep beat_length end
First we define two functions (using the term def) and then we can call them by their names to get them to do their thing. A function is just a set of instructions that you can reuse later. You might also hear them called methods, procedures, subroutines, or callable units.
Let’s try something with parameters.
# Drum loop eight, with parameters def play_a_beat(chosen_sample, beat_length) sample chosen_sample sleep beat_length end 4.times do play_a_beat(:drum_cymbal_closed,0.25) end
The variables chose_sample and beat_length are passed to the function when it is called.
Now see if you can figure out what this next section of code will do, and then run it to check if you’re right.
# Drum loop nine, nested functions def cymbalClosed(beat_length) sample :drum_cymbal_closed sleep beat_length end def loop_this(n) n.times do cymbalClosed 0.25 end end loop_this 16
One more thing, if you want your beat to go on forever, or until you stop it, try this.
# Drum loop ten, in_thread beat_length = 0.25 in_thread do loop do sample :drum_heavy_kick sample :drum_cymbal_closed sleep beat_length sample :drum_snare_hard sample :drum_cymbal_closed sleep beat_length end end
So now you know the basics of creating beats in Sonic Pi. Show your friends.
If you’d like to play with electronic drum machines and make different rhythms, check out free drum machines such as:
WebAudio Drum Machine (online)
Keezy Drummer (iOS)
DMach (Android)
Hydrogen (Windows, Mac, or Linux)
GarageBand (iOS or Mac)
HammerHead (Windows)
