Intervals · Step 7
Major and minor third
Four semitones sounds bright and open; three sounds darker and closer. That is not decoration — it is the thing you are learning to hear, and it comes faster with a song attached. Any tune you know by heart will do, as long as you can hum its first two notes: a rising major third opens “When the Saints Go Marching In”, a rising minor third opens “Greensleeves”.
Once an interval has a song, you stop counting and start recognising. Hear the two notes, ask which opening they match, and answer. The names on the buttons are the intervals; the sound in your head is the song. A few rounds of this and the right button starts to feel obvious before you have thought about it.