Intonation Training means to tell accuracy of pitches. Many people going through this process quickly realise that this can be somewhat subjective - one persons in tune is may or may not really be in tune to others, and it is not always convenient to have other people to help out. This app provides a more objective reference for training. A first step is to listen to same note played twice, with the second time identical, or a little different from the first. The next step is to listen for pitching with 2 notes, for listening to relative pitching of the intervals. Upcoming is a next step for harmony, with 3 or 4 distinct notes, a chord.