Comments on the Differential-Electrode Technique

The theory of differential electrode technique is briefly reviewed, especially as it pertains to the recording of remote CM. Median isopotential curves for the first and third turn electrode placements are given for 18 guinea pigs. The differences and similarities between differential and single intracochlear as well as round window electrodes are discussed. Special attention is paid to the CM that is recordable from the third turn at high frequencies with differential electrodes. On the basis of dc polarization experiments, it is concluded that this high frequency CM is not a local response. Some performance criteria for the evaluation of the adequacy of differential electrodes are developed.