For example, minor chords sound more somber, more serious, than major chords. Why? Because of the way the intervals are "stacked" within the chord. A diminished chord sounds suspenseful, tense, nervous. An augmented chord has a distinctive sound, too. Learn how to hear, feel, and identify these chords, as well as extended chords (you'll learn how to listen for the "color tone" in any 4-note chord).
Here are the color tones we'll listen for:
Once you can identify the 4 types of triads, and then recognize the color tones, it is a short step to recognizing chords such as minor 7ths, minor 6ths, diminished 7ths, major 9ths, and so on.