Role of short-term memory in loudness comparisons

Abstract

In an earlier study of the auditory discrimination of time-varying noise bursts [Ellermeier and Schrödl, J. Acoust. Soc. Am. 108, 2596 (2000)], listeners were found to place greater weight on the beginning and end of the sounds than on the middle portion. To investigate whether this outcome is due to primacy and recency effects in short-term memory which tend to be sensitive to manipulations of the inter-stimulus interval (ISI), the ISI separating the two noise bursts in a 2IFC task was varied systematically. Six participants performed loudness comparisons on 1-s samples of white noise randomly changing in level every 100 ms. In different blocks of trials, the two noise bursts to be compared were either separated by a 500-ms or a 2-s ISI. COSS analysis [Berg, J. Acoust. Soc. Am. 86, 1743–1746 (1989)] of the overall loudness judgments revealed elevated weights for the beginning and end of the noises, as in the earlier study. These weighting patterns were largely unaffected by the manipulation of ISI, suggesting that the temporal weights found characterize loudness integration in general, and are not just due to idiosyncrasies of the timing used in the 2IFC procedure.