I am just beginning an ear-training course, part of The David L. Burge Ear-Training Library. I am impressed so far. It is in about 16 tapes or some comparable number of CDs.
I am taking their Relative Pitch Course, and my wife, a professional classical pianist, is deeper into taking their Perfect Pitch course. She is extremely impressed.
It's published by American Educational Music Publications, Music Resources Building, 1106 East Burlington Avenue, Fairfield IA 52556. (515) 472 3100. They have a website, but I can't find the URL. You should be able to finding it using your search engine(s).
Dave Oesterreich