I'm not a linguist, but I can see a connection between speech impairment and language learning.
I'm asking because I have a slight speech impairment myself (unable to pronounce guttural sounds like Guh, or Tuh, also 's' sounds like 'sushi' or 'sausage'). This is due to physical constraints/left side face paralysis due to surgery I have had in the past. Although as I age I have become increasingly more aware of this which has helped, I guess.
I have been to a speech therapist before without much luck. I was young and through my naivety found saying the same stupid phrase over and over again, a drag (and still do :P). They said my hearing has become attuned to thinking I sound normal. I was thinking lately however about learning a new language but I am concerned that I might end up learning it incorrectly. Will it be more beneficial to try and sort out my English first (if I can) or see if I can push the reset button on a new language?