Profile analysis and ripple discrimination at high frequencies

Abstract

Profile analysis and spectrotemporal ripple discrimination are psychoacoustic tasks used to probe the auditory system’s spectral and intensity resolution. In the present experiment, we compared performance at low- and high-frequencies in four related psychoacoustic tasks: level discrimination, profile analysis, spectrotemporal ripple detection, and spectrotemporal ripple direction discrimination. The level discrimination and ripple detection tasks were designed so that cues from single auditory filters were sufficient for performing the tasks. The profile analysis and ripple direction discrimination tasks were designed to render cues from single auditory filters insufficient to perform the tasks. Based on data from a group of ∼20 young normal-hearing, listeners, we found that profile analysis was markedly worse at high-frequencies than low-frequencies, even when accounting for differences in level discrimination at low- and high-frequencies. In contrast, no significant differences were observed between low- and high-frequencies for either the ripple detection or ripple direction discrimination tasks. We further analyzed our behavioral data using computational simulations of auditory-nerve and midbrain responses. This analysis suggested that differences in performance at low- and high-frequencies cannot be explained at the level of the auditory periphery, but instead emerge at more central loci. [Work supported by NIH grants F31 DC019247 and R01 DC005216.]