Behavioral and electrophysiological measures of stimulus envelope and fine structure contributions to the binaural masking level difference

Abstract

The goal of this study is to establish electrophysiological methods for estimating the relative contribution of stimulus envelope and fine-structure cues across a range of clinical populations using a binaural masking level difference (BMLD) paradigm. Stimulus envelope cues were manipulated by the using narrowband noise maskers (50 Hz) with the inherent envelope fluctuations of Gaussian noise (GN) or the reduced envelope fluctuations of low-noise noise (LNN). Fine-structure cues were manipulated by choosing signal frequencies and masker center frequencies of 500 and 4000 Hz. The availability of fine structure cues to the auditory system differs markedly between these two frequencies. Electrophysiological measures consisted of far-field evoked potentials targeting the P1-N1-P2 cortical components. Stimulus maskers were presented continuously at a spectrum level of 60 dB SPL while signal level was varied in descending steps. Threshold was estimated as the lowest signal level that generated a reliable N1-P2 ...