Pre-change stimulus duration modulates acoustic change complex amplitude without affecting latency in normal-hearing adults

Introduction The acoustic change complex (ACC), a cortical auditory evoked potential, reflects the brain's ability to detect changes in an ongoing sound. This study investigates the influence of pre-change stimulus duration on the ACC in normal-hearing adults. Methodology Twenty normal-hearing adults (10 men, 10 women) participated. ACC N1-P2 responses were recorded using a 1,000 Hz base tone that increased by 12% in frequency with pre-change durations ranging from 1,000 to 5,000 ms. Linear mixed models were used to evaluate effects of pre-change duration and sex on ACC amplitude and latency. Results ACC N1-P2 amplitudes significantly increased with longer pre-change durations, with 5,000-ms stimuli yielding amplitudes 2.3 times larger compared to those evoked by a duration of 1,000 ms. Female participants showed significantly larger ACC N1-P2 amplitudes and shorter N1 latencies compared to male participants across all durations. Conclusion Longer pre-change stimulus durations increased ACC N1-P2 amplitudes while latencies remained stable. Durations ≥3,000 ms produced consistently robust responses, but duration choice should balance response strength with testing efficiency. Further work is needed to determine how these effects generalize across populations and clinical settings.