No there is no way that I know of to change the language (maybe you could check with the Spanish publisher, though). There was a third party hack for the German language version to get the text in English, but the voices remained in German.
At some point after the last localization release, it is possible there could be some kind of official DLC / patch / addon to allow switching languages. Larian hasn't even hinted about that, though, and I'm not sure how enthusiastic various publishers would be if it would be a significant amount of extra work for them.