It is a collection of questions to listen to chords(Chord dictation/music dictation). There are 4 types of chords for each question. All 150 questions. The answers can be checked not only by the chord name but also by the score. The difficulty level is Advanced level. It covers from 4 chords to tension note. The APP [Chord Hearing A] is Beginner and intermediate ver. Is a free app, so try it first and you will find it useful. In addition, for convenience of display area, the flat is indicated by "b".