The phenomena liable for acoustic damping in thermo-acoustic instabilities in liquid rocket engines are investigated. Modelings to account for the nozzle impedance, in compact hypothesis, and for the visco-thermal losses at walls are derived according to the Galerkin framework, where pressure variations are decomposed over the acoustic eigenmodes. Models are implemented in a low order tool and compared successfully to analytic and numerical predictions. The turbulent/acoustic interaction, responsible for acoustic absorption at the jets, is reviewed, and an in-progress strategy is presented.