Informational masking: Toward improved understanding

Abstract

This paper is concerned with simultaneous informational masking of tones by tone complexes. Past work distinguishes between energetic (peripheral) masking, which occurs when target and masker overlap in the peripheral frequency channels, and informational (central) masking, which can occur even when there is no such overlap but there is uncertainty in the frequency spectrum of the stimulus. We suggest that this distinction is (1) applicable to domains other than the frequency domain (e.g., the spatial domain) and (2) relative to the level of processing in the auditory system considered. We further suggest that this distinction can be rigorously defined for any domain and any level by comparing performance of the ideal detector operating on the inputs at that level to human psychophysical performance. We also argue that informational masking is strongly influenced by target-masker similarity and segregation difficulty, not only by stimulus uncertainty. Experiments designed to probe this issue are discussed in a companion paper (Mason et al.). Finally, ideas relevant to the large intersubject differences observed in informational masking (focused on the distinction between trying to hear the target and trying to not hear the masker) are used to make new predictions about these differences. [Work supported by NIH/NIDCD.]