Probing the semiconductor-insulator interface with small pulse excitations superimposed on a quiescent bias, which is changed stepwise, a fingerprint of the transient relaxation of the interface states is obtained. Using the deep level transient spectroscopy technique (DLTS) for a time constant filtering, a series of peaked signals provides the thermal activation energy and the magnitude of charge relaxation transitions. In addition, a peak deconvolution yields different predominant processes. Peculiarities of the full width at half maximum plotted vs. the quiescent bias are related to a change of the prevailing mechanism. At least three typical branches of the transient response of the Si-SiO2 interface were detected by a peak shape analysis. In order to confirm the universality of the findings, capacitance and charge transient measurements with two different DLTS systems have been performed.