An audio recording apparatus that improves atmospheric acoustic conditions by method of processing sound forms presented directly or non directly to either the front or rear of the device. The fingers are made from steel and the base is made from cast aluminum. The friction stir welding apparatus also includes a first shoulder not substantially rotatable relative to the spindle housing about the axis and a second shoulder not substantially rotatable relative to the spindle housing about the axis. The rotor tends to rotate relative to the stator to maximize the inductance of an energized winding.