This work describes the behaviour of the standard deviation of pressure fluctuations in fluidized beds for group B particles in the bubbling regime. An empirical–theoretical function, which depends on the gas velocity, is proposed for predicting the pressure signal fluctuations, and the corresponding values of are calculated. The differences in the standard deviation of pressure fluctuations obtained for absolute or differential sensors are analyzed and compared to experimental values corresponding to different bed dimensions, pressure probe positions and particle properties.This work has been supported by the National Energy Programme of the Spanish Ministry of Education under the project number ENE2006-01401 and by the Universidad Carlos III de Madrid (CCG06-UC3M/ENE-0764).Publicad