The Performance of the Acoustic Change Complex Versus Psychophysical Behavioral Measures: A Systematic Review of Measurements in Adults.

Objectives: The acoustic change complex (ACC) is a cortical auditory evoked potential that shows promise as an objective test of the neural capacity for speech and sound discrimination, particularly for difficult-to-test populations, for example, cognitively impaired adults. There is uncertainty, however, surrounding the performance of the ACC with behavioral measures. The objective of this study was to systematically review the literature, focusing on adult studies, to investigate the relationship between ACC responses and behavioral psychophysical measures.

Design: Original peer-reviewed articles conducting performance comparisons between ACCs and behavioral measures in adults were identified through systematic searches. The review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for reporting, and the methodological quality of the included articles was assessed.

Results: A total of 66 studies were retrieved that conducted adult ACC measurements, of which 27 studies included performance comparisons. Meta-analysis revealed a total of 41 significant correlations between ACC responses (amplitudes, latencies, and thresholds) and behavioral measures of speech perception (2 weak, 28 moderate, and 11 strong correlations), and 12 significant moderate/strong correlations were identified with behavioral measures of frequency discrimination.

Conclusions: This systematic review finds that ACC responses are associated with speech perception and frequency discrimination, in addition to other types of sound discrimination. The choice of evoking stimuli, ACC outcome measure, and behavioral measure used may influence the strength and visibility of potential correlations between the objective (ACC) and behavioral measures. The performance of the ACC technique highlighted in this review suggests that this tool may serve as an alternative measure of auditory discrimination when corresponding behavioral measures prove challenging or unfeasible.