It is well known that the interactions between a coherent light and a scattering medium produce a speckle pattern. But, even if intensity and phase statistics have been already well described for a long time, the statistics of the increments of the phase spectrum have never been explored. In this paper, we firstly introduce these concepts before demonstrate that phase spectrum increments contain informations on the medium observed. Moreover, we show that phase spectrum increments allow reaching informations on the media which are not present in the classical approaches based on the intensity. Monte Carlo simulations are used to this aim.