And a comment on experiences learning languages - 'phonetic element peculiar to non-native languages' means very unusual sounds. The Salish-Quinault language from several posts above, has two phonemes that you simply cannot distinguish from one another-- when you grow up speaking English. Your brain lost the neural pathway along the way to acquire English.
If ever I find the reference it will put this to bed. IMO.
Zooby - were you learning languages that come from your branch of the language tree?
If you do more than skim some of these references I posted you might notice that related languages share lots of phonemes.