You are aware how electrostatic membranes function, right? On traditional constant charge drivers such as the ones Stax builds, the membrane is highly resistive and single ended. The bias supply is high impedance (as in it has little to no current to give) so the bias is just "pushed" onto the diaphragm. There is no flow as it is an open circuit so it's hard for it to get rid of a large charge that just sits there in one of the isolated "hot spots" which appear, mostly due to the uneven resistivity of the diaphragm.