The present invention provides a processor or signal processing module that features one or more modules configured to receive an input signal containing information about the unsteady pressures or acoustic emissions caused by a medium flowing through a pump, and also configured to provide of an output signal containing information about the performance of the pump. The information about the performance of the pump may include information about pump performance monitoring by a slip flow measurement, about predicting impeller wear, about pump impeller cavitation monitoring, about pump monitoring through acoustic emissions, about pump leak detection, about pump efficiency monitoring and about positive displacement pump monitoring.