sound, syntax, vocabulary

Of the three, I think sound is the most important for comprehension. Although syntax is important, I cannot think of a situation in which syntax was the root of a miscommunication. Vocabulary, I think, can sometimes be an issue, but it is generally resolved through context. Even if someone uses a word I'm not familiar with, usually I am able to guess its meaning or at least come close. Sounds, however, cause real miscommunication issues. I have recorded two instances in my data notebook so far, and both have had their root in sound differences. Also, both involved foreign students whose pronunciations of common words were just different enough that I didn't get it, even when they repeated themselves.