||In this paper a comparison between pressure fluctuations measurements in the time domain is proposed. These measurements were carried out on two centrifugal turbomachines, a fan with air and a pump with water. In order to gather a better understanding of their internal acoustics, time records of the pressure fluctuations were made on the blades in the outlet of the impellers and near the volute tongue. These showed that the flow is very unsteady at the impeller outlet and in the tongue region. An analysis of the pressure fluctuations and their propagation showed that the main noise sources are caused by the blade-tongue interactions and depend on the fluid type. In the case of the pump, the hydraulic nature of the noise source is dominant. Using a one-dimensional propagation model, it is possible to explain some differences in the behaviour of the turbomachines which is related in particular to the different sound speeds.