Discrete time tube models describe the propagation of plane sound waves through the vocal tract. Therefore they are important for speech analysis and production. In most cases discrete time models without losses have been used. In this contribution loss effects are introduced by extended uniform tube elements modeling frequency dependent losses. The parameters of these extended tube elements can be fitted to experimental and theoretical data of the loss effects of wall vibrations, viscosity and heat conduction. For the analysis of speech sounds the parameters of a lossy vocal tract model are estimated from speech signals by an optimization algorithm. The spectrum of the analyzed speech can be approximated well by the estimated magnitude response of the lossy vocal tract model. Furthermore the estimated vocal tract areas show reasonable shapes.