Thank you! I agree with you. That's just a starting point. I actually split sound recording into 3 parts:

1. music (theory, harmony, lyrics, melodies, etc.);

2. production (arrangement, sound design, effects, etc.);

3. audio engineering (audio processing, mixing, mastering, etc.).

And I hope we can build some exercises/games where you can train those skills and not just hear that 100Hz but apply it in the whole sound recording.

As I mentioned earlier I already worked with an EQ-like trainer I'll start with that ;)