Fan-Gang Zeng is Associate Professor of Biomedical Engineering at University of California, Irvine. Richard R. Fay is Director of the Parmly Hearing Institute and Professor of Psychology at Loyola University of Chicago. Arthur N. Popper is Professor in the Department of Biology, Director of the Neuroscience and Cognitive Science Program, and Co-Director of the Center for Comparative and Evolutionary Biology of Hearing at the University of Mayland, College Park.