Greybody factors are frequency dependent quantities that measure the deviation from the perfect black body spectrum of Hawking radiation, and they provide us with valuable information about the near horizon structure of black holes. In
addition, when black holes are perturbed the geometry of spacetime undergoes dumbed oscillations.
Quasinormal modes, with a non-vanishing imaginary part, provide us with the frequencies and the dumbing times of
these oscillations, and since they do not depend on the initial conditions, they carry unique information about the few
black holes parameters. I will discuss both greybody factors and quasinormal modes under scalar perturbations of the BTZ black hole as well as of the Eistein-Born-Infeld dilaton black hole, which is inspired from Superstring Theory,
and I will present exact analytical expressions for both quantities in both models.