This paper is concerned with a theoretical study of a vibrated particle bed. The study covers greater ranges of vibratory intensity and bed height than previously treated in the compressible gas model of a vibrated particle bed. The extension of the parameter ranges has been made possible through the use of an accurate equation of continuity as opposed to a simplified one for a boundary condition. The equation of continuity has been incorporated into the boundary condition together with an equation of motion. Two modes of contact between the particle bed and the vessel base are clearly defined and the mathematical implication of dealing with the contact is described. A parametric study was then conducted with those physical properties that characterize the behaviour of a vibrated particle bed: the vibratory intensity, bed height, vibratory frequency and particle size. Experiments were also conducted to measure the air pressure beneath vibrating particle beds, and were compared with the model predictions. Measurements have been found to agree satisfactorily with predictions over broader ranges of parameter values than those studied formerly.