Interference from degraded auditory stimuli: Linear effects of changing-state in the irrelevant sequence

Cognitive performance, particularly on a number of tasks involving short-te rm memory for order, is impaired by the mere presence of irrelevant backgro und sound. The current study examines the features of the irrelevant sound that determine its disruptive potency. previous research suggests that the amount of variability in an irrelevant stream is related to the degree of d isruption of memory. The present experiments used a parametric approach to manipulate degree of change more precisely. Increasing levels of degradatio n, effected either by low-pass filtering (speech) or by digital manipulatio n (speech and nonspeech), monotonically decreased the degree of interferenc e. The findings support the following propositions: (i) the degree of physi cal change within an auditory stream is the primary determinant of the degr ee of disruption; and, (ii) the effects of irrelevant speech and irrelevant nonspeech sounds are functionally similar. (C) 2000 Acoustical Society of America. [S0001-4966(00)02809-5].