But note that most real world sounds are a combination of many frequencies, so training on sine waves may not be what you want.

I would think that training on them provides useful skills that generalize more broadly. It's probably not perfect but it's easy to create cards with binary choices that can get progressively more difficult.

The goal is getting to a point where I engage into deliberate practice of distinguishing sounds and using Spaced Repetition to do it.

If anyone who's good at sounds has better ideas about creating a Anki deck to train distinguishing sounds, I would be happy to hear ideas.

I also try to train phonemes, but creating good cards for it proved to be hard. The first cards I created where simply to hard for myself as I'm not good at audio perception.

I can hear a lot more in a Salsa song than I could hear 5 years ago. I think that it's worthwhile to invest significant time in getting to perceive more bits of reality in daily life. I'm still at the phase of experimenting about how to train myself and others to have richer qualia, but I think it's an area worthy of further investigation.

Pitch seems to me like a very straightforward concept, but I'm also willing to learn other ways of distinguishing sounds.