There are two types of minimal pairs in each trainer.  For example, in the Russian trainer there are Russian-Russian pairs (those will be valuable to anyone studying Russian), and English-Russian pairs (Those are optimized for English speakers, but I believe they'd be valuable to pretty much anyone studying Russian). 

The main reason I might not recommend the English->Russian trainer to someone who doesn't speak any English would be that the English-Russian pairs might be frustrating because they're asking students to tell the difference between TWO sound sets that are unfamiliar. Also, maybe more importantly, the trainers all start with ~45 minutes of instructional videos on how Russian pronunciation works, and if you couldn't understand anything from those videos, that'd be frustrating, too.  But if you feel quite comfortable with English, you’re not likely to run into either of those problems.

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