One of the most important intervals for hearing harmony and chord quality. Major thirds are what give music brightness, light and open sound, and they’re a key part of major chords and melodies. As you listen, pay attention to the warm, uplifting feel of the interval and how it immediately suggests a major sound. You’ll hear major thirds everywhere, in melodies, chord progressions, harmonies, and riffs and once your ear locks into this interval, it becomes much easier to recognize major chords in real music.