The present application discloses detecting an asperity on a storage media surface using two amplitude threshold crossings of an asperity detection signal within a preset timing window. The present application further discloses a temperature-dependent resistive asperity sensor and a preamplifier that correlates a resistance change at the asperity sensor within a preset timing window to detect an asperity on a storage media surface. The asperity may be one or both of a void in the storage media surface and a protrusion from the storage media surface.