Effects of Click Duration on the Latency of the Early Evoked Response

The effect of click duration on the latency of waves I, III, and V was investigated by testing 20 normal-hearing subjects at 60 dB HL using electric pulses of 25, 50, 100, 200, and 400 µs. Alternating condensation and rarefaction clicks were used. The results revealed similar and nonsignificant latency differences for the 25-, 50-, and 100-µs pulses. However, the 100 µs duration is preferred to the 25-µs pulse because the latter reduced the maximum measurable hearing loss by about 13 dB. The results also showed that latencies increased approximately 0.10 ms as duration increased from 100 to 200 µs and by 0.20 ms when duration increased from 100 to 400 µs. Although such differences by themselves are small, they can combine with other stimulus or recording variables to be clinically significant. Therefore, it is important to control click duration when normative data are generated. A second experiment was conducted to assess the interaction of polarity (condensation, rarefaction, and alternating) and pulse duration (100 and 400 µs) on the wave V latency. These data revealed no latency differences among polarities at either duration.

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