The effect of a noble metal (silver or copper) island film on the vibrational spectrum of a natural aluminum oxide nlm was studied using the reflection-absorption spectroscopy technique. It was found that the intensity of the absorption band of aluminum oxide near 950 cm(-1) changes drastically after the deposition of the metal overlayer. This band intensity increases rapidly with increasing of the silver film thickness more than twice. reaching the maximal value at the silver thickness 0.2 nm. then the band does not change up to the thickness similar to 2 nm. Such behavior takes place only in the presence of aluminum under oxide film. We suggest that this: increase of the absorption band intensity is due to the increase of the aluminum oxide film thickness, caused by an electrochemical reaction resulting in aluminum anodic oxidation. For thicker silver films the intensity of the aluminum oxide band falls down slowly due to a metal screening effect.