Efficacy of long latency auditory evoked/event-related potentials (AEP) in phonetic perception tasks.

Abstract

Latency functions for the auditory evoked potentials N100, P200, and the auditory event-related potential P300 were explored to determine their efficacy as indicators of neurologic processing time for the recognition of differences in three divergent levels of acoustic phonetic patterns. Stimuli consisted of digitally reproduced and altered pairs of spoken numbers with either acoustically identical (four, five with identical /f/), acoustically similar (four, five with natural /f/), or acoustically dissimilar initial phonemes (eight, two). Each stimuli pair was presented in a traditional 80%/20% AEP ‘‘oddball’’ paradigm. For the experimental group of 20 normal-hearing adult subjects, no statistically significant differences were observed in N100 or P200 waveform latency among the three levels of acoustic divergence. P300 latency exhibited significantly greater intersubject variability as phonetic acoustic divergence increased. Suggestions of possible brainstem or subcortical processing aspects, as well as subject-variable alternative processing strategies, are presented.