Gabriel Wyner, in his book Fluent Forever, stresses the importance of minimal pair training early in the language learning process. He summarizes the research behind this suggestion in this video.
His book details how to create these cards for use in Anki. He also makes some cards available on his web site in the form of "Pronunciation Trainers", available or purchase (I've never used them, I cannot recommend them).
The problem I find is that Anki always presents the cards in a predictable order. This means that, given two sounds, A and B, I know I will always be presented with A first, then B. Even if I “try” to forget this, it’s impossible--especially for new cards, when I see the same set of cards 4 times in a row.
Also, after a few days, if I miss a review card, it will be even easier to cheat. Suppose I miss ‘A’. A moment later I come across ‘B’ and I know which one it is, and answer correctly, pushing that card forward for a month.
Now for the next month, every time I see that card, I know it’s ‘A’ without even listening to it.
Is anyone aware of a tool that overcomes this problem? I would be happy with a way to make Anki not behave this way, but I think this is a long shot. So another tool would be ideal (even one I pay for).