Informational masking as a function of masker set size

Abstract

Thresholds for the detection of a 1000-Hz tone added to informational maskers were measured using six-tone maskers. A large number of different maskers were generated by randomly choosing the frequencies of the six tones from a (log) uniform distribution ranging from 100 to 6000 Hz, exempting the 160-Hz frequency range surrounding the 1000-Hz signal. These maskers were then assigned to different masker sets, with the number of maskers in any one set being 3, 6, 12, or 24. Thresholds were measured separately for the different masker sets. Unlike the method used by Wright and Saberi [J. Acoust. Soc. Am. 105, 1765–1775 (1999)], on each interval the masker was drawn with replacement. For small set sizes, the trials could be segregated into those in which the maskers were different across intervals and those in which the maskers were the same across intervals. The resulting thresholds did not depend on the masker composition in the two intervals. As the set size increases, the observers ability to remember/identify the maskers is diminished but the average thresholds are not obviously altered by changes in set size beyond 3. [Work supported by NIH.]