I spent a lot of time this long weekend making improvements to my perfect pitch training app: https://pganssle.github.io/cim/
I'm pretty happy with how it's shaping up. My son has been using it 4-5 times per day (the sessions are frequent but short), and it's kind of amazing to see how good he is at identifying chords.
It is all open source and designed to be easy to fork and deploy if desired: https://github.com/pganssle/cim
If you are good at web design or music theory I'd be very happy to see contributions (including just giving feedback)! Doesn't take much to be better at those things than me... 😛 ([Exhibit A](https://github.com/pganssle/cim/issues/9) 😅)
@pganssle tried this out, and it was fun! Relative pitch is enough to do it though? Bit skeptical of the "absolute pitch" claims, bit it seems useful and fun for relative pitch
@marcogorelli To be clear this is for teaching children to have perfect pitch. I think there are some implied claims there about a critical period for learning perfect pitch. l am also mildly skeptical of the somewhat grandiose claims in the paper (100% success rate for all children who completed the program), but I have always been very interested in things that alter your perception of the world, and if there is a critical period I wanted to make sure I got in there.
My son is getting really good at it at this point, and there's at least one other person actively using the app who is a bit ahead of him who can get perfect scores on at least the first 9 levels.
@marcogorelli I think for adults there are established techniques for improved ear training. I am not sure if simply doing those as often as we do the chord identification method trainer would give a similar probability of attaining perfect pitch. It seems like kids with early exposure to music are pretty significantly more likely to get perfect pitch and have the kind of intuitive relationship to music that a lot of musicians have, so it might be that pretty much any sort of ear training will work when you start this young.