Nina Kraus1, Trent Nicol2. 1. Hugh Knowles Professor of Neurobiology, and Communication Sciences at Northwestern University, Frances Searle Building, 2240 Campus Drive, Room 2-346, Evanston, IL, 60208-2952, USA. nkraus@northwestern.edu. 2. Research Associate at Northwestern University, Frances Searle Building, 2240 Campus Drive, Room 2-356, Evanston, IL, 60208-2952, USA. tgn@northwestern.edu.