A dead-end filtration set-up with a vertically vibrated medium is used to study cake permeation. A key feature of these experiments is that a sudden increase in permeability at a certain critical vibration amplitude takes place, when the static loading is light. A theory to explain this phenomenon is put forward in terms of a relation to local fluidization near the medium, thus returning the clogged septum resistance to virtually its unclogged value. The fluidization is due to a particle stress induced by the vibration of the particle fluid mixture near the medium. This stress can be large enough to counteract the compressive stress that is caused by gravity and drag due to the fluid flow in the set-up. Estimates for the particle stresses are obtained; these are proportional to the amplitude decay inverse length lambda. The latter is derived from the analysis of a vibrated particle-fluid mixture that is in a state of fluidization. It is argued that only in this state will the value of lambda be large enough to generate the required particle stress. A much smaller value for lambda is obtained when the particles in the medium make enduring contacts. The theory predicts a frequency dependence for the turnover point in the permeability according to the root of the applied frequency. This theoretical result is confirmed by the experiments. The theory also predicts that when the decay is too steep, so that the vibration amplitude vanishes at a distance of less than a particle diameter, no fluidization will occur. This is found to be true for larger cake masses. (C) 2003 Elsevier Science Ltd. All rights reserved.