The dead band is the insensitivity or unresponsiveness of a sensor in a specific range of input signals. In that range, the output may remain near a certain value (generally zero) over the entire dead band zone. An input can be varied through this range without causing any measurable output response. Dead band is usually expressed in percent of span. The term sensitivity has frequently been used to denote the dead band, but the terms are not truly interchangeable. Sensitivity refers to the reaction of the sensor while dead band refers to range in which it doesn't react.