Knight Capital Quantitative Analyst interview questions

I was first sent a math/programming test to solve from home. After passing the test I was interviewed three times over the phone. I got rejected after the third interview. I thought the written exam was fairly complex, but doable. The first two interviews went well, but the third one did not. I couldn't understand what the interviewer was saying so I didn't properly answer some of his questions (I am not a native english speaker, and neither was he).