Selective attending to auditory streams in complex sequences: Frequency and/or temporal expectations?

Abstract

Both frequency and temporal information influence the perceptual organization of complex sequences: stream segregation is more likely with wider frequency separations and at faster rates. The influence of frequency and temporal information in directing attention to a stream within a complex sequence is investigated. Complex sequences of three subsequences (each with a specific frequency/tempo combination) were preceded by a cue sequence containing different types of information (FT=frequency + tempo, F=frequency, T=tempo, S=silence). The ability to selectively attend to one subsequence was measured by correct detections of a small temporal irregularity in the cued subsequence. When stream segregation was easy (large frequency separations), performance was similar for FT and F (93%), intermediate for T (79%) and random for S (64%): frequency information facilitated selective attending more than temporal information. When stream segregation was hard (small frequency separations), performance was poorer and similar for all conditions (65%): temporal information became predominant when frequency information was less useful. Thus listeners adapt their attending strategies to coincide with the most pertinent information. Results are discussed in terms of diverging predictions of the theories of Bregman [1990] and Jones [1993].