The Add9 Sound
A major 2nd, then a major 2nd, then a minor 3rd — and 5 near misses, each a single tone away.
The chord-quality drill loads here.
Built upward, the add9 is a major 2nd, then a major 2nd, then a minor 3rd — 4 tones in all. In a drill it arrives in a key you did not choose, so the only thing left to listen to is that shape.
Near missesmajor triad, sus2, major 7th, dominant 7th and major 6th chord — each one is this chord with a single tone moved, which is why a wrong answer here is almost never random.
It sits in the colour tier — one tone moved off a triad you already know.