  We investigate black holes in a class of dRGT massive gravity for their quasi
normal modes (QNMs) for neutral and charged ones using Improved Asymptotic
Iteration Method (Improved AIM) and their thermodynamic behavior. The QNMs are
studied for different values of the massive parameter m_g for both neutral and
charged dRGT black holes under a massless scalar perturbation. As m_g
increases, the magnitude of the quasi normal frequencies are found to be
increasing. The results are also compared with the Schwarzchild de Sitter (SdS)
case. P-V criticallity of the aforesaid black hoels under massles scalar
perturbation in the de Sitter space are also studied in this paper. It is found
that the thermodynamic behavior of a neutral black hole shows no physically
feasible phase transition while a charged black hole shows a definite phase
transition.
