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5 Properties of Intervals

In my researching, studying and thinking about music theory for the last 35 or so years, I have come up with this framework for understanding intervals and by extension, all of music.

These are not rules, they are observations, that will help you to make sense of what is happening in music.

  1. Gravity
  2. Mirroring
  3. Symmetry
  4. Size
  5. Melodic Probabilites

Property 1: Gravity

The more you hear of one note, the more gravitational force this note exerts on the other notes you hear. This leads to Keys having the “home” feel of the root of a key, and the feeling of resolution when the melody lands on the root note again.

Property 2: Mirroring

From any note, if you make a jump up of any interval less than 1 Octave, its mirror image consists of the same note one octave down.

For example, from a C3 if you jump up to a G3 (a jump of 7 semitones), and then jump down one octave, you land on a G2, 5 semitones below C3.

So the mirror image of a 5th jump up is a 4th jump down.

Every interval has a mirror image. Mirror images always go together and share the opposite “vibe” or “feel” (except for an octave or a #4 which has the same vibe, see below in Symmetry).

Property 3: Symmetry

From any note, if you make a jump up of any interval, the jump down of that same interval gives you the symmetrical interval.


For example, from C3 jump up a 5th you get a G3, jump down a 5th you get an F2. These two interval jumps are symmetrical.  Symmetrical intervals all share the same kind of “vibe” or “feel” with each other.

There are only two intervals up to 1 octave for which the symmetrical interval and the mirror image are the exact same note:

An octave – jump up or down one octave and you land on the same note

A #4 (or b5, same thing) – jump up or down a #4 and you land on the same note.

Property 4: Sizes of Intervals

Intervals can be small, medium or big.

Small intervals: 4 semitones or less

Medium intervals: 5-7 semitones

Big intervals: 8 or more semitones

Property 5: Melodic Probabilities

This property says any medium or big jump in a melody is most likely followed by a small jump. Small jumps are statistically more common than big jumps. Big jumps create tension and surprise, whereas small jumps resolve them and create a nice flow.

Learn more on my Music Theory For Electronic Musicmakers Course:

https://courses.zoid.ie/music-theory-level-1

Thanks, Bye!
ZOiD

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