The effect of oxygenation through the round window membrane was estimated using polarographic technique and the combined action potential of the inner ear. The calculated amount of oxygen permeable through the round window membrane (14% in room air and 80% in pure oxygen) revealed to have very limited effect in maintaining the inner ear potential. Carbogen inflation in maintaining the N1 potential during asphyxia was significantly effective only at 8 kHz. Oxygen supply by this route, however, may enable the inner ear tissue alive even in misery perfusion and recover the high tone potential as a therapy of otitis media with effusion.