In this paper, we consider the use of seismic sen- sors for footstep localization in indoor environment. A popular strategy of localization is to use the measured time differences of arrival (TDOA) of the source signal at multiple pairs of sensors. In the literature, most of these algorithms assume that the perceived propagation velocity is constant. However, in dessipative and dispersive media, such as concrete, the measured propagation velocity of an impulsive perturbation depends highly on the source position. Traditional algorithms based on TDOA and velocity estimation cannot so be used for footstep localization using elastic waves. In this paper, we propose a new localization algorithm adapted to provide good localization results in dissipa- tive and dispersive medium using only the sign of the measured TDOAs and that does not need the estimation of the propagation velocity. Simulation results are included to assess performances of the new sign of the time differences of arrival (SO-TDOA) algorithm.