Embodiments are directed to a method for use in ultrasound imaging of matter in a region comprising providing wave energy into the region and transducing wave energy returned from the region to form a set of receive signals defining received signal data. The method comprises separating linear and nonlinear components of the received signal data based on a second order Volterra model. The method also comprises computing an estimate of a tissue acoustic nonlinearity parameter, B/A, using a ratio of the nonlinear component to the linear component, and identifying tissue characteristics of the matter in the region using the B/A.