Experiments done in developing absolute pitch (AP) have produced mixed results. In the experiment conducted by Brady (1970), the level of absolute pitch achieved by using reference and series training techniques was unsubstantiated. Reference vs. series training are forms of relational development of which reference training uses a framework of high, medium and low pitches to continually refer back to, while series training has no framework and becomes somewhat random; thus making it harder to find significant advancements in the subjects’ AP skills. The large relational factor involved when listening to varying pitches was not optimal for learning the skills needed. Rather, chroma identification skills are required for true AP identification tasks (Rush, 1989).
In the experiment described by Rush (1989), twenty-six college music majors were trained on AP for one academic year using a method developed by Burge (1983). The method emphasized the chroma, or color as mentioned, when notes in the musical diminished seven pattern were presented one at a time using a timbre familiar to the subject. The trainee started with minimal pitches in the exercises, and graduated one pitch at a time as s/he learned the chroma for each of the twelve semitones. Eventually, once a high level of correct responses were achieved, the timbre auditory object was altered during testing to ensure the subjects could achieve the same level of correct responses on any timbre. All experiment hypotheses were confirmed. Non-possessors of AP pitch needed training in this area of chroma identification, in order to successfully acquire AP.