I'm not so sure about it. I can understand where you trying to go with it but it just doesn't seem to work well for me.
Maybe its the choice of colours being wrong, the n is definately out of context with the other colours. If you look at your main desig bit its all bold impact type colours and then the n is some wishy washy blue/grey colour.
If you wanted to play with colours, try doing a purely monotone version as this could have far more impact than the multiple colours you're currently using.
Another thing to consider is whether or not the poster is meant as a quick in your face impact or whether you want people to have to think to get its true meaning - it took me a couple of seconds to click that the letters made design.
Theres also more than one type of recognised sign language off the top of my head too - IIRC theres an american and a british english sign language. So taking that into consideration for an intended market might be worthwhile too.