FIG. 1.

A schematic diagram showing the four measurement buffers used to derive the ECAP waveform of the fifth pulse in a pulse train. Condition A includes five equal pulses at the test rate, four being maskers (black) and the last one being the probe pulse (red). Condition B includes only the four masker pulses of A. Subtraction of B from A gives the ECAP and artifact for the fifth pulse. Condition C contains the probe pulse preceded by a masker pulse that has a level 10 CL higher than the probe pulse and a short interpulse interval of 500 μs and D contains the masker pulse of C on its own. Subtraction of D from C gives the probe artifact, which can then be subtracted from the difference between A and B to obtain the artifact-free probe response to the fifth pulse.