Method for rheological characterization of a viscoelastic medium, comprising the following steps: (a) an excitation step during which a vibratory excitation is generated in the viscoelastic medium leading to a deformation of the medium, (b) a deformation measurement step during which the deformation of the medium caused by the excitation is observed, (c) and a characterization step during which at least one non-zero power parameter y is determined such that a rheological parameter of the medium x is equal to x(f ) = a + b.fy, where f is the frequency, a is a real number and b a non-zero scale parameter. It is thus possible to obtain mapping of the power parameter y.