Comparison of Four Approaches to Age and Gender Recognition for Telephone Applications. - Florian Metze; Jitendra Ajmera; Roman Englert; Udo Bub; Felix Burkhardt; Joachim Stegmann; Christian A. Müller; Richard Huber; Bernt Andrassy; Josef G. Bauer; Bernhard Littel (ICASSP (4), 2007)