Pressure fluctuations induced by gas discharge through an upward nozzle in a fluidized bed have been studied with the objective of setting up a new experimental technique for evaluating a characteristic length of the jetting region. Pairs of pressure signals were recorded simultaneously on the jet axis and at the bed side wall at the same distance from the distributor. The statistical analysis of the signals allowed the fluidized bed operating conditions to be associated with the characteristics of the signals in the frequency domain, and the characteristic height of the jet to be determined. The analysis also supported the evaluation of the jet height by means of direct comparison between the fluctuations of static pressure on the axis and at the wall. The features of the technique are discussed and compared with those of previously proposed techniques for measurement of the jet penetration length. It was found that the characteristic height conforms with the definition of penetration length based on the concept of jet momentum dissipation.