Most of us in LA know at least a little Spanish and can recognize the sounds and simple expressions anyway. Here in Barcelona you don’t know if you don’t understand because they are speaking that BarTHElona accent or because you don’t know the vocabulary or you don’t understand because they are not speaking Spanish!
Catalan is the first language in Barcelona. It was one of those Quebec-style revolts that has ended in favor of the non-national language.
This is a good example of the differences, the first sentences being in Catalan and the second in Spanish.