Abstract: The invention presents methods and instrumentation for measurement or imaging of a region of an object with waves of a general nature, for example electromagnetic (EM) and elastic (EL) waves, where the material parameters for wave propagation and scattering in the object depend on the wave field strength. The invention specially addresses suppression of 3rd order multiple scattering noise, referred to as pulse reverberation noise, and also suppression of linear scattering components to enhanced signal components from nonlinear scattering. The pulse reverberation noise is divided into three classes where the invention specially addresses Class I and Class II 3rd order multiple scattering that are generated from the same three scatterers, but in opposite sequence.