Detection of static and dynamic changes in interaural correlation

Abstract

This study examines the relation between a static and a dynamic measure of interaural correlation discrimination: (1) the just noticeable difference (JND) in interaural correlation and (2) the minimum detectable duration of a fixed interaural correlation change embedded within a single noise-burst of a given reference correlation. For the first task, JNDs were obtained from reference interaural correlations of + 1, -1, and from 0 interaural correlation in either the positive or negative direction. For the dynamic task, duration thresholds were obtained for a brief target noise of +1, -1, and 0 interaural correlation embedded in reference marker noise of +1, -1, and 0 interaural correlation. Performance with a reference interaural correlation of +1 was significantly better than with a reference correlation of -1. Similarly, when the reference noise was interaurally uncorrelated, discrimination was significantly better for a target correlation change towards +1 than towards -1. Thus, for both static and dynamic tasks, interaural correlation discrimination in the positive range was significantly better than in the negative range. Using the two measures, the length of a binaural temporal window was estimated. Its equivalent rectangular duration (ERD) was approximately 86 ms and independent of the interaural correlation configuration.

Human Auditory Cortical Processing of Changes in Interaural Correlation

“…These estimates are similar to those derived from behavioral measurements (Culling and Summerfield, 1998;Akeroyd and Summerfield, 1999;Boehnke et al, 2002). The different integration times required for 13 and 03 transitions might conceivably be implemented by a single mech-anism with a variable integration time.…”

“…03 transitions were reported as movement toward the center of the head, whereas 13 transitions were described as a single focused source that is "stretching" and moving away from the center toward the two ears. The fact that the interaural correlation change was perceived as gradual, although the physical change was abrupt, may be an indication of the existence of a sliding binaural temporal integration window (Culling and Summerfield, 1998;Akeroyd and Summerfield, 1999;Boehnke et al, 2002), over which the perceived IAC value is computed. This is further discussed below.…”

“…Several behavioral studies have measured listeners' ability to discriminate interaural correlations (Pollack and Trittipoe, 1959a,b;Gabriel and Colburn, 1981;Culling et al, 2001;Boehnke et al, 2002). Just-noticeable differences are not uniform across the IAC range: they are small (typically 0.04) when measured as differences from an IAC value of 1 and are an order of magnitude larger when measured as differences from an IAC value of 0.…”

Decorrelation Sensitivity of Auditory Nerve and Anteroventral Cochlear Nucleus Fibers to Broadband and Narrowband Noise

“…Figure 11 shows ⌬ thresholds toward correlation 1, from base correlation ϭ 0. The box shows the range of reported human correlation jnds from base correlation 0 (Gabriel and Colburn, 1981;Boehnke et al, 2002); the black horizontal line shows the median of the reported thresholds. When compared with thresholds from base 1, thresholds from base 0 show a similar CF dependence, are generally higher, and exhibit smaller differences between AN and TB fibers.…”

“…In psychoacoustic studies, sensitivity to interaural correlation has been measured extensively and systematically by mixing independent noise sources (Pollack and Trittipoe, 1959a;Gabriel and Colburn, 1981;Koehnke et al, 1986;Bernstein and Trahiotis, 1996;Culling et al, 2001;Boehnke et al, 2002). Single-neuron sensitivity to such stimuli, in which the normalized correlation is the primary parameter varied, has received little attention.…”