Detecting the mid-latency auditory evoked potential during stimulation at several different sound pressure levels

Abstract

Current approaches for auditory screening are usually based on the Brainstem Auditory Evoked Potentials or on the Otoacoustic Emissions, and hence are not able to detect pathologies that affect higher auditory centers. Therefore, the Middle Latency Auditory Evoked Potential (MLAEP) was investigated as a neurophysiologic acoustic threshold measure by using the "Evoked Potential Detector" (EPD) as an Objective Response Detection technique. The EEG was collected from ten adults during monaural click stimulation (left ear, using contralateral masking noise) with different sound pressure levels. Based on the statistical distribution of EPD under the null hypothesis (absence of response), the use of the critical value considering EEG as a colored noise and fitting the shape parameters for a Beta distribution resulted in an objective detection of MLAEP with a better specificity and a similar sensitivity than considering EEG as a white noise. Full detection over all the casuistry occurred for stimulation levels as low as those found in literature using expert-based analysis, particularly for the derivation contralateral to the stimulation. This finding suggests the use of EPD for detecting MLAEP response as an auxiliary tool for determining objectively the neurophysiologic acoustical threshold level. © Springer-Verlag Berlin Heidelberg 2007.