A parameter of a fluid passing through a pipe is measured using a spatial array of sensors disposed at different axial locations along the pipe. The spatial array includes at least two overlapping sub-arrays. Using the pressure signals, a signal processor determines a spatial correlation matrix for each of the sub arrays. The spatial correlation matrices from the sub-arrays are averaged, and the averaged spatial correlation matrix is used as input to an adaptive array processing algorithm. The pipe may be open ended such that it can be positioned within the fluid flow for forming a portion of a sensing device.