Table 2:

Summary of experimental procedure for the four methods

Method Number	Method Name	Description All voltages are peak to peak
1	High-Low	Start block suprathreshold at 10 V or 16 V. Decrease in 1 V decrements until twitches return.
2	High-Low-High	Start block suprathreshold at 10 V or 16 V. Decrease in 1V increments until twitches return. Continue to decrease until 2 V below first threshold. Increase in 1 V increments until twitches disappear
3	Binary	Search a range from 0-16V starting in the middle at 8V. Two possible next steps: 1) If complete block achieved then values above 8V eliminated and test middle of remaining range, from 4V. 2) If complete block was not achieved, then values below 8 V eliminated and test middle of remaining range, or from 12V. Repeat steps 1 and 2 until block threshold is determined within a 1V resolution
4	Random	Test block values in a randomly generated order within the below ranges (ranges based on preliminary data from animal # 1): 10 kHz: 2-9 V 20 kHz: 4-11 V 30 kHz: 5-12 V