Intervals by Ear
Two notes, one distance, one answer — and a published list of exactly which other distances it gets stolen by.
The interval drill loads here.
What this drill trains
An interval is the distance between two pitches, and it is the smallest unit your ear can be tested on. Thirteen of them fit inside an octave, from the unison to the octave itself, and each one keeps its character no matter what key it lands in — which is exactly why the drill never tells you the key. What you are learning is a shape, not a note name, and a shape survives transposition.
How to run it
Pick a level, press play, name what you heard, and let the round tell you what you actually said. The scoring is not the point; the pattern in the mistakes is. Almost nobody confuses a semitone with an octave — the errors cluster one step either side, and on the inversion, which is the same pair of notes arriving the other way up. Every leaf page publishes that confusion set, so you can drill a distance against the ones that steal it rather than in isolation.
Where to go next
Once a distance is reliable on its own, it starts turning up inside chords — which is where the chord-quality drill picks it up. If you are choosing between hearing two notes together or one after the other, read together or one after the other first.