Effect of acoustic overstimulation on the hydropic ear

The effect of acoustic overstimulation (2 kHz pure tone) on the compound action potential (CAP) threshold was investigated at frequencies ranging from 2 to 16 kHz using albino guinea pigs, both normal and with experimentally induced endolymphatic hydrops. The hydropic ears were less susceptible to acoustic overstimulation than the normal ears. As the CAP threshold was raised, the frequency exhibiting the greatest CAP threshold shift increased in both animal groups. The tendency was more noticeable in the hydropic ears than in the normal ears. These results are discussed from the aspect of cochlear hydrodynamics.