1. Department of Radioelectronics, Czech Technical University in Prague, Technická 2, 166 27 Prague 6, Czech Republic
2. Section of Physiological Acoustics and Communication, Department of Otolaryngology, Eberhard-Karls-University Tübingen, Elfriede-Aulhorn-Strasse 5, 72076 Tübingen, Germany
3. Department of Nuclear Chemistry, Czech Technical University in Prague, Břehová 7, 115 19 Prague, Czech Republic