You're shown four brief melodies in plain quarter notes. They are similar but the pitches are slightly varied in each. One of the variants will be played. Which one? You can press "play" to hear the melody as many times as you like. Enter your answer by touching the box A, B, C, or D.
If you choose the wrong one, you'll have a chance to hear both your choice and the right one for comparison.
As with most of these exercises the melodies are invented anew each time you run the program, so they are not predictable.