Surface waves with a frequency of 0.5-2.5 Hz were generated on a homogeneously fluidized bed. The propagation velocity and rate of attenuation of the induced pressure fluctuations were measured using signal averaging techniques. The measured wave velocity and attenuation rate correlated well with predictions based on a theory which considers the bed as an incompressible liquid with low viscosity. From the rate of attenuation an effective bed viscosity was calculated between 1.2 and 6.0 Pa.s. At high frequencies the wave generator produced high-amplitude density waves.