A unified view of the temporal-window and the adaptation-loop model in conditions of forward- and simultaneous masking

Abstract

Two different mechanisms have been discussed in the literature as a possible explanation for forward masking: persistence (or temporal integration) and adaptation. In this study, two well established models of temporal processing in the auditory system are compared in a unified modeling framework. The temporal-window model representing a temporal-integration mechanism and the adaptation-loop model as the representative for the adaptation mechanism. The unified modeling framework shared a compressive, non-linear auditory filter stage and a template-based (optimal detector) decision stage. Predictions from both models were obtained in conditions of forward masking at 1 and 4 kHz for masker-to-signal gaps of 0 to 160 ms, and in conditions of simultaneous masking, where the signal was temporally overlapping with the masker. The signal was a 10- or 12-ms raised-cosine ramped pure tone and the masker a 200-ms broadband noise. It was found that when both models are adjusted to behave similarly, the two mechanisms can be considered as being essentially equivalent. In fact, the combination of integration and the signal-to-noise-ratio based detection criterion in the temporal-window model can be interpreted as adaptation. Suggestions for a unified model of auditory processing are presented. [Work supported by the Danish Research Council.]