Figure 3.

Different techniques to separate the electrical stimulus from the much smaller electrically evoked compound action potential (eCAP) neural response. By alternating the polarity of the stimulus and averaging, the stimulus will cancel out while the eCAP remains. This technique is used in the Advanced Bionics system. The template subtraction method collects a template of the stimulus at a subthreshold level and subtracts it from the recording after scaling. The forward masking subtraction method is used in the Cochlear device and uses a 2-pulse stimulus. The probe in (B) will not produce a physiological response because the nerves are assumed to be in the refractory period after the presentation of the masker. From Brown.⁶ Copyright John Wiley & Sons Limited. Reproduced with permission.