Over the years, Combustion Instability in solid rocket motors has been an unsolved problem. Combustion Instability can be referred to as an oscillatory amplification to high-pressure levels which causes damage to the motor, levels down the engine efficiency and destroys the burner. This is due to the interaction between the acoustic field and unsteady heat release. One of the simplest methods to acquire combustion instability-related data is the T-Burner setup which does not require a full-scale motor. A T-Burner primarily focuses on pressure-coupled responses which are usually longitudinal oscillations. This research reports experimental and numerical works on oscillatory pressure measurements using T-Burner which is comprised of a few test firings with various lengths and diameters. Double-base propellants are tested in the setup to measure the acoustic losses using pressure sensors at the ends. Further using MATLAB software, important variables are characterised such as the decay constant and growth constant which further calculates admittance and response function.