Funnily enough, I’ve been doing these exercises for years, and teaching them to my students for years for ear-training purposes. I thought I’d made them up. Oh well. Indeed, as the writer of Ecclesiastes aptly said, “there is nothing new under the sun” (Eccl. 1:9)! There’s a timeless truth that might go something like this: “If it works, it just works.”
Yet I hereby deflect any due props to Nadia Boulanger, for these her “Sequential Exercises.” I respectfully grant her the credit, because she published these in one form or another. Nearly 100 years ago. Not only does she predate me, but she certainly had a lot more education, experience, and mastery than I do!
If these exercises can be of help to you, here they are. Use for improving your ear, relative pitch, fixed pitch, vocal control, and breath control.
They are also available here (Public Domain). You may freely download them.