An electrochemical noise method, apparatus and system calculates parameters of interest related to corrosion rates of an electrically conductive article. The method involves placing a test electrode, a reference electrode, and an auxiliary electrode in an environment of interest; placing the test electrode under potentiostatic control regime for a potential scan; measuring the relationship of current v. potential (polarization resistance, Rp) of the test electrode relative to the reference electrode during a first period; switching from potentiostatic control to the open circuit potential (OCP) of the test electrode; monitoring the OCP of the test electrode during a second period; determining ΔI from the relationship Rp=ΔV/ΔI, where ΔV is measured over a second period of time; and calculating the localized corrosion from the measured potential and current data.