Chapter 05 of VJ Manzo's book  Max/MSP/Jitter for Music is about constructing an application for ear training with musical intervals. I have separate screenshots for each of the twelve steps in this exercise but I've condensed them into a single video below.

[youtube=https://www.youtube.com/watch?v=I1UhAQ8N7GQ]

Completed:

• Max/MSP/Jitter for Music, Ch. 05: Interactive Ear Training (12 exercises)
• Patches can be downloaded from http://db.tt/GBYLb0vY (Dead Link)
• UPDATED LINK: Patches can now be downloaded from http://j.mp/1iy19Xl