Lateralization of two-transient stimuli

Precedence-effect thresholds for a population of untrained listeners as a function of stimulus intensity and interclick interval

“…The ICI was 2 ms. This value has been shown to produce a strong precedence effect for impulsive sounds ͑Wallach et Zurek, 1980;Zurek and Saberi, 2003͒, and was selected to be near the training value used by Saberi and Perrott ͑1990͒.…”

“…These patterns are often complex and may result in ambiguous position cues ͑Zurek and Saberi, 2003;Saberi and Perrott, 1995͒. Others have also shown that a number of observations related to the precedence effect may be accounted for by examining the complex pattern of cross-correlation activity resulting from dual-pulse stimuli ͑Saberi and Perrott, 1995;Henning, 1998, 1999;Hartung and Trahiotis, 2001;Zurek and Saberi, 2003͒. The loss of the signal cue may also be related to adaptation ͑Hafter et al, 1988͒, or modulation of attention or other cognitive factors ͑Clifton, 1987; Hartmann and Rakerd, 1989;Blauert and Col, 1991͒.…”

“…One such view postulates neural inhibition as a mechanism for reduction of spatial cues ͑Lindemann, 1986a, b; Hafter et al, 1988͒, particu-larly when the lead and lag waveforms contain overlapping spectral energies ͑Shinn- Cunningham et al, 1995;Saberi, 1996͒. Another approach suggests that peripheral processes including interactions within auditory filters and the interaural phase spectrum can account for many features of the precedence effect, particularly when transient stimuli are employed ͑Saberi and Perrott, 1995;Henning, 1998, 1999;Hartung and Trahiotis, 2001;Zurek and Saberi, 2003͒. Other evidence, however, points to a complex process involving high-order influences. One striking example is the Clifton effect ͑1987͒; Clifton and her colleagues have demonstrated a failure of the precedence effect when the position of the lead and lag sources are reversed between successive presentations ͑Clifton and Freyman, 1989͒.…”

“…These experiments have shown that when the effect fails, it takes several seconds for it to be built up, implicating a slow centralized process. Further evidence against a hard-wired explanation is provided by studies that show learning ͑Saberi and Perrott, 1990͒ and top-down influences when cross-correlation cues are ambiguous ͑Zurek and Saberi, 2003;Saberi and Perrott, 1995;Freyman et al, 1997͒. Related phenomena in localization, such as the Franssen effect ͑1960͒ which demonstrates onset dominance in reverberant environments lasting tens of seconds, are also thought to be driven by such cognitive factors as plausibility ͑Hartmann and Rakerd, 1989͒. Because these diverse findings are inconsistent with a single explanation, current views consider the precedence effect to incorporate several onset phenomena, which in turn has necessitated multiple approaches to its study ͑Blauert, 1997; Djelani and Blauert, 2001͒; The reader is referred to Blauert and Col ͑1991͒ for a discussion of irregularities in a͒ Current address: Department of Cognitive Sciences, University of California, Irvine, CA 92697.…”

“…The current study uses a population approach to study precedence in which we examine thresholds from a large number of untrained listeners. The study was motivated by observations of large variability across threshold estimates in several experiments, particularly from naive subjects, that appear statistically nonstationary and difficult to attribute to sensory inhibition ͑Saberi and Perrott, 1990;Zurek and Saberi, 2003;Henning, 1998, 1999͒, and by discrepant findings between Saberi andPerrott ͑1990͒ andLitovsky et al ͑2000͒ related to the effects of practice on lag-click ITD discrimination.…”