1. Department of Mathematics, Seattle University, Seattle, Washington 98122, USA
2. Cluster of Excellence “Hearing4all” and Research Centre Neurosensory Science, Department of Neuroscience, School of Medicine and Health Science, Carl von Ossietzky University, Oldenburg, Germany
3. Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, New York 10461, USA