Listen to the next portion of the audio file, and mark off the next formal section that you want to use (mine is from Qtractor's measure 25 to beat to of measure 38). The portion that I chose is also repeated, like the first part.
Place the blue markers at the beginning and end of the segment that you chose.
Create a new MIDI clip.
Create the notes separated by three beats, as in the last segment. This time, be sure to add two notes at the same time, by ensure that they are aligned vertically. Again, it doesn't matter which pitches you choose, because they will be randomized.
Select all of the pitches, and randomize them by using the "Randomize MIDI" tool.
Depending on how the pitches are randomized, each pair of notes will probably end up in one of the following situations:
They are too close or share a particular intervallic relationship that makes them sound like one note.
They are too far or share a particular intervallic relationship that makes them sound like two notes.
They share a particular intervallic relationship that makes them sound like one chord built of two equal chords.
Depending on your aesthetic preferences, you may wish to change some of the notes so that one or some of these situations are avoided.
I created the tone cluster at the end by clicking arbitrarily across bar 37. It happened to create six notes with the pitches G, E, C-sharp, F-sharp, G-sharp, and B. I could have used the "Randomize MIDI" tool, but chose not to.
Then I carefully click-and-dragged the right-most end-point of each pitch, so that they all ended at the same time: the first beat of measure 38.
When you're done, you may need to copy-and-paste the segment.
