This work is a study of the interaction between the fluidized-bed dynamics and the pressure and flow pulsations from the air-supply system. The interaction has been identified as a key process to understand in order to correctly formulate inlet boundary conditions in numerical modelling of fluidized beds, operated under industrial conditions. The interaction between pressure waves, resulting from activities in the bed, with pressure and flow pulsations from the air-supply system is a main mechanism that gives rise to formation of a coupled system: of fluidized bed, air plenum, pipe, flow control devices and fan. A general model of the response of the fluidized bed to disturbances has been formulated, and the information with respect to the dynamics of the bed and the bed plus the entire air-supply system, has been investigated. Different modes of bubble flow have been studied in the time-frequency plane (wavelet analysis), aiming at localizing the phenomena of interest in time. A model of the air- supply system has been coupled with three- dimensional numerical simulations of the flow field in the bed and the air plenum.