Published results on the velocity of propagation and the change of amplitude of dynamic waves in fluidized beds are reviewed and re-evaluated. A distinction is drawn between pressure waves and solids concentration waves. Over the range of frequencies of interest in fluidized beds, predictions of the velocity of compression waves by pseudo-homogeneous models and by models which treat the two phases separately differ little. Therefore the experimental results are compared against the simpler pseudohomogeneous models. The behaviour of dynamic waves is inconsistent with models which ignore particle-particle contacts. To distinguish unambiguously between compression and dynamic waves, experiments at elevated pressure are needed. The results are not consistent with pseudo-homogeneous description of compression waves.