Distinguishing between other peoples voices may seem like a trivial task. However, if those people are speaking a language you dont understand, it becomes much harder. Thats because you rely on individuals differences in pronunciation to help identify them. If you dont understand the words they are saying, you dont pick up on those differences.

That ability to process the relationship between sounds and their meanings, also known as phonology, is believed to be impaired in people with dyslexia. Therefore, neuroscientists at MIT theorized that people with dyslexia would find it much more difficult to identify speakers of their native language than non-dyslexic people.

via Recognizing voices depends on language ability – MIT News Office.