I personally found this to be super helpful: https://www.perplexity.ai/search/i-am-not-musically-trained-and-iaSZpB0FS9SMhrxh...
How Quartal Harmony Works
- Pick any note to start (for example, C).
- Count up four notes (including your starting note) in the musical alphabet: C (1), D (2), E (3), F (4). So, C to F is a fourth.
- From F, count up four notes: F (1), G (2), A (3), B♭ (4). F to B♭ is a fourth.
- Stack as many fourths as you like for a bigger, more “open” sound.
How to Compose with Quartal Harmony
- Start with any note as your root.
- Add another note a fourth above.
- Add another note a fourth above that.
- Play all these notes together for a quartal chord.
- Move the whole shape up or down to create progressions.
“Quartal harmony involves the use of a series of fourths in a sequence. At the very least, it involves two notes separated by fourths. For example, playing C and F together produces a sound that characterizes quartal harmony. If you stack another fourth (B♭) on top of the C and F, you get a typical quartal harmony voicing.”