Abstract: A method of controlling the depth of immersion of an oxygen lance in a molten bath within an electric arc furnace where noise emitted from the furnace during lancing in an acoustic spectrum ranging between 1 kHz and 15 kHz defined by a plurality of selected frequency bands is monitored. The position of the lance with respect to the bath surface is controlled by reference to the amplitudes of the output signals emitted from each of the selected frequency bands. There is a distinct change in the relationship of particular bands to provide a "lance out" signal which is directed to a control for a lance drive mechanism. Apparatus for practicing the method includes a microphone, a filter unit, a microprocessor and a lance drive responsive to signals from the microprocessor.