One of the best ear training methods I’ve come across is functional ear training. Instead of learning to recognize the sound of individual intervals, with functional ear training you focus on learning the specific sound of a note in the context of tonality. Instead of identifying intervals, the goal of functional ear training is to figure out how the note or notes in question relate to the key center at hand. Fot that you need not only the “notes in question” but a reference point – be it a drone, a backing track, a background chord.