The full set
Ordered by semitone count below. Each entry has a quick character note and the song mnemonic Aubel surfaces in-app. The ones with full written guides are linked. We're adding the rest as we go.
- Unison Same pitch, played twice. Read the guide →
- Minor 2nd One semitone. The leading tone resolving up (7 to 1, ti to do). Read the guide →
- Major 2nd Two semitones. Adjacent scale degrees (1 to 2, do to re). Read the guide →
- Minor 3rd Three semitones. The defining interval of minor chords. Read the guide →
- Major 3rd Four semitones. The defining interval of major chords. Read the guide →
- Perfect 4th Five semitones. 1 to 4 (do to fa), or 5 up to the next 1 (sol to do). Read the guide →
- Tritone Six semitones. The 4-to-7 (fa to ti) inside dominant 7 chords. Wants to resolve outward. Read the guide →
- Perfect 5th Seven semitones. 1 to 5 (do to sol). The strongest tonal move. Read the guide →
- Minor 6th Eight semitones. 5 to the flat 3 above. Inversion of the major 3rd. Read the guide →
- Major 6th Nine semitones. 1 to 6 (do to la). Inversion of the minor 3rd. Read the guide →
- Minor 7th Ten semitones. The flat 7 of the dominant 7 chord. Read the guide →
- Major 7th Eleven semitones. 1 to 7 (do to ti). One semitone shy of the octave, leaning up. Read the guide →
- Octave Twelve semitones. Same pitch class, frequency ratio 2:1. Read the guide →
How they unlock
Aubel starts every player on four intervals: unison, perfect 4th, perfect 5th, and octave. Those four are far enough apart that they rarely get confused with each other in the first week. The next interval unlocks when you've mastered everything in your current pool, and mastery is two things at once: ten lifetime correct answers on each interval, holding 70% accuracy over your recent attempts. Strong recent form on too few reps doesn't unlock; neither does grinding reps at low accuracy. If you keep bouncing off ear-training apps without ever building that consistency, here is why, and what to do about it.
The order from there: major 3rd, major 6th, major 2nd, major 7th, then the minor intervals (3rd, 2nd, 6th, 7th), and the tritone last. The sequence isn't arbitrary; each new interval arrives with at least one well-trained anchor on its doorstep, and the tritone waits until "the unstable one" is a one-step decision.
A few things that confuse most people
Enharmonic equivalents: an augmented 4th and a diminished 5th sound identical. Both are tritones. The two names matter for notation, not for ear training.
Inversions: every interval pairs with one other interval that sums with it to an octave. The major 3rd pairs with the minor 6th. The perfect 4th pairs with the perfect 5th. Inverted intervals sound related, not identical.
Compound intervals: distances larger than an octave (a 9th, 10th, 11th, 13th) collapse back to their simple form for ear-training purposes. A major 10th is an octave plus a major 3rd. The 13 intervals on this page cover everything.