Time-Intensity Trading in the Late Auditory Evoked Potential

The present study investigated physiological correlates of the time-intensity trading relationship in late components (N1, P2) of the auditory evoked potential. Late-potential and behavioral thresholds were estimated in five normal-hearing, young adult participants for 1000- and 4000-Hz tone bursts having durations of 8, 16, 32, 64, and 128 ms. The results showed that late-potential thresholds decreased by an average of 24 dB for 1000-Hz conditions and 18 dB for 4000-Hz conditions. Behavioral thresholds also improved by about 22 dB and 18 dB for 1000-Hz and 4000-Hz conditions, respectively. The slope of improvement for both late-potential and behavioral thresholds was on the order of -4 to -6 dB per doubling of stimulus duration, depending on stimulus frequency. Stimulus duration also influenced latency and amplitude measures of the N1 and P2 components such that response latency decreased and amplitude increased as stimulus duration increased. The present results demonstrate a time-intensity trading relationship in components of the late potentials that is consistent with previous psychophysical and physiological data.