Fig. 6

Block thresholds versus frequency for both electrode types. For all waveform shapes, BT increased linearly versus frequency (regression equations for bar platinum and carbon black-coated electrodes, respectively: 0.29*frequency + 0.9, R² = 0.7; 0.26*frequency + 0.01, R² = 0.6). Overall, there is a significant reduction in BT due to application of carbon black coating (* p < 0.001)