Chord ear training
Chord quality is decided by the third, so if you can hear thirds you can already hear most chords.
Recognising a chord by ear is a smaller job than it looks, because chord quality is decided almost entirely by the third. If interval work has given you major and minor thirds, most of this follows.
Start with two
Major and minor triads. They differ by one note moving one semitone, and that difference is the most audible thing in harmony.
Play them back to back on any instrument. Then have something play them at random and name them. Most people get reliable at this within a couple of weeks of short daily practice — it is the fastest win in ear training.
What to listen for: the major third sits bright, the minor third darker. Resist the "happy/sad" shorthand once you are past the first week — plenty of minor-key music is not remotely sad, and leaning on emotional labels stops working as soon as context complicates them.
Then the two unstable ones
Diminished — two stacked minor thirds. It sounds compressed and tense, and audibly unfinished: it wants to move.
Augmented — two stacked major thirds. It sounds suspended and directionless, because it divides the octave evenly and no note claims to be the root.
Both are easy to notice and harder to tell apart at first. The distinguishing cue: diminished feels like it is squeezing inwards, augmented like it is stretching outwards.
Then sevenths
Four types cover nearly everything:
| Chord | What to listen for |
|---|---|
| Dominant 7 | Major triad plus tension. Sounds like it is pointing somewhere. |
| Major 7 | Major triad plus a soft, hazy sheen. Relaxed, not pulling. |
| Minor 7 | Minor triad, but rounder and less mournful than a plain minor. |
| Half-diminished | Diminished flavour but less brittle. |
The most useful discrimination is dominant 7 versus major 7, because they behave in opposite ways. The dominant leans; the major seventh sits still. If a chord sounds like it wants to resolve, it is almost always a dominant.
Two things that make this much easier
Hear them in context, not isolation. A chord played alone is harder to identify than the same chord in a progression, because in context its function gives it away. Practise both, but do not assume isolated chords are the "proper" version of the skill — context is how you meet chords in real music.
Sing the root. Before naming the chord, sing what you think the root is. That single habit anchors the rest and stops you guessing from vague colour.
Beyond quality
Once quality is comfortable, the next steps are hearing inversions — which note is in the bass — and hearing progressions as functional movement rather than a series of separate chords. Progressions tend to come more easily than isolated inversions.