In a method for determining an operating frequency of a touch screen unit a first set of sinusoidal signals may be provided to a plurality of electrodes of a touch screen, each sinusoidal signal in the first set of sinusoidal signals having a first frequency, and a first value indicative of the amount of current flowing from the plurality of electrodes when the touch screen is not being touched by a person and when the first set of sinusoidal signals is provided to the plurality of the electrodes may be determined. A second set of sinusoidal signals may be provided to the plurality of electrodes of the touch screen, each sinusoidal signal in the second set of sinusoidal signals having a second frequency, and a second value indicative of the amount of current flowing from the plurality of electrodes when the touch screen is not being touched by the person and when the second set of sinusoidal signals is provided to the plurality of the electrodes may be determined. An operating frequency of sinusoidal signals to be provided to the plurality of electrodes may be determined based on the first value and the second value.