Responses of Auditory Cortical Neurons to Pairs of Sounds: Correlates of Fusion and Localization

Mickey, Brian J.; Middlebrooks, John C.

doi:10.1152/jn.2001.86.3.1333

Cited by 41 publications

(14 citation statements)

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“…Barn owls and cats have emerged as two key models for animal studies on the PE (Cranford 1982;Dent et al 2005;Keller and Takahashi 1996;Litovsky and Yin 1998a,b;Mickey and Middlebrooks 2001;Spitzer and Takahashi 2006;Tollin and Yin 2003a,b;Tollin et al 2004;Yin 1994). Researchers have combined behavior and physiology in these animals to more accurately characterize the important features of the stimuli and listening environment under situations that have been shown to produce the PE behaviorally in those species.…”

Section: Introductionmentioning

confidence: 99%

Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

Dent¹,

Tollin²,

Yin³

2009

Journal of Neurophysiology

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Dent ML, Tollin DJ, Yin TC. Influence of sound source location on the behavior and physiology of the precedence effect in cats. J Neurophysiol 102: 724 -734, 2009. First published May 13, 2009 doi:10.1152/jn.00129.2009. Psychophysical experiments on the precedence effect (PE) in cats have shown that they localize pairs of auditory stimuli presented from different locations in space based on the spatial position of the stimuli and the interstimulus delay (ISD) between the stimuli in a manner similar to humans. Cats exhibit localization dominance for pairs of transient stimuli with ͉ISDs͉ from ϳ0.4 to 10 ms, summing localization for ͉ISDs͉ Ͻ 0.4 ms and breakdown of fusion for ͉ISDs͉ Ͼ 10 ms, which is the approximate echo threshold. The neural correlates to the PE have been described in both anesthetized and unanesthetized animals at many levels from auditory nerve to cortex. Single-unit recordings from the inferior colliculus (IC) and auditory cortex of cats demonstrate that neurons respond to both lead and lag sounds at ISDs above behavioral echo thresholds, but the response to the lag is reduced at shorter ISDs, consistent with localization dominance. Here the influence of the relative locations of the leading and lagging sources on the PE was measured behaviorally in a psychophysical task and physiologically in the IC of awake behaving cats. At all configurations of lead-lag stimulus locations, the cats behaviorally exhibited summing localization, localization dominance, and breakdown of fusion. Recordings from the IC of awake behaving cats show neural responses paralleling behavioral measurements. Both behavioral and physiological results suggest systematically shorter echo thresholds when stimuli are further apart in space. I N T R O D U C T I O NThe precedence effect (PE) is an auditory illusion thought to be responsible for a listener's ability to localize sounds accurately in the presence of echoes in reverberant environments. Laboratory studies on the PE typically mimic a somewhat simplified version of a natural listening situation where a sound (lead) and its echo (lag) are delivered from loudspeakers positioned at different spatial locations, times, or intensities to the listener's ears. Three perceptual phases of the PE have been mapped out by a number of studies. At a 0-ms lead-lag delay, the listener perceives only one fused sound at a position midway between the locations of the lead and the lag. As lead-lag delays increase, the perceived location of the fused auditory image moves toward the leading source until ϳ1 ms when it is perceived at the actual location of the leading source. This phase of the PE is known as summing localization. In the phase known as localization dominance, a single fused auditory image is perceived only at the location of the leading stimulus, as if the spatial information about the lagging source location had been suppressed. Depending on a number of characteristics, this phase lasts for lead-lag interstimulus delays (ISDs) ranging from 1 to ϳ10 ms . The upper end of loc...

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Section: Introductionmentioning

confidence: 99%

Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

Dent¹,

Tollin²,

Yin³

2009

Journal of Neurophysiology

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“…The precedence effect holds for binaural as well as monaural conditions, including along the vertical and frontback axes ͑Blauert, Rakerd et al, 2000͒. In spite of an extensive history of theoretical ͑Lindemann, 1986a, b; Zurek, 1980Zurek, , 1987Freyman et al, 1997;Saberi, 1996;Hartung andTrahiotis, 2001͒, neurophysiological ͑Cranford andOberholtzer, 1976;Yin and Litovsky, 1995;Mickey andMiddlebrooks, 2001͒, applied ͑Blauert, 1989;Muncey et al, 1953͒, and even clinical ͑Hochster and Kelly, 1981͒ research, the mechanisms underlying the precedence effect are not well understood. For reviews see Gardner ͑1968͒, Zurek ͑1987͒, and Litovsky et al ͑1999͒.…”

Section: Introductionmentioning

confidence: 99%

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

Saberi

Antonio

2003

The Journal of the Acoustical Society of America

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Data are reported from 127 untrained individuals under lag-and single-click conditions in a precedence-effect task. In experiment I, each subject completed ten runs in a two-interval forced-choice design under a lag-click condition and three runs under a single-click condition. The cue to be discriminated was an interaural time difference ͑ITD͒. Stimuli were 125-s rectangular pulses and the interclick interval ͑ICI͒ was 2 ms. Subjects were randomly assigned to three groups of approximately 30. Each group was tested at one stimulus intensity ͑43, 58, or 73 dB͒. Mean threshold within each group was greater than 500 s for lag-click ITD conditions, although substantial intersubject variability and a clear effect of stimulus intensity on lag-click ITD thresholds were observed, with lower thresholds for higher intensities. In experiment II, the ICI was varied from 0.3 to 10 ms, and thresholds were obtained from groups of approximately 20 untrained subjects. Data were also collected from three highly experienced observers as a function of ICI. The best naïve subject produced mean thresholds near, but not as low as those obtained from experienced subjects. Analysis of adaptive-track patterns revealed abrupt irregularities in threshold tracking, consistent with either losing the cue or listening to the wrong cue in an ambiguous stimulus.

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“…These questions can be addressed by examining the neural responses to lead/lag pairs. There are a growing number of neurophysiological studies of the precedence effect in a variety of species and auditory structures (Yin 1994;Fitzpatrick et al 1995;Keller and Takahashi 1996a,b;Litovsky 1998;Litovsky and Yin 1998a,b;Fitzpatrick et al 1999;Mickey and Middlebrooks 2001;Litovsky and Delgutte 2002;Spitzer et al 2004;Tollin et al 2004), and nearly all of these studies report that a cell's response to the lag source is weaker than its response to the lead source or to a single source and that this response recovers at longer delays. Such suppression at short delays is a possible candidate for the decrease in sensitivity to the binaural cues of later arriving sounds experienced by human listeners (Zurek 1980;Stecker and Hafter 2002).…”

Section: Object Localization Amidst Echoesmentioning

confidence: 99%

Object localization in cluttered acoustical environments

et al. 2008

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In nature, sounds from objects of interest arrive at the ears accompanied by sound waves from other actively emitting objects and by reflections off of nearby surfaces. Despite the fact that all of these waveforms sum at the eardrums, humans with normal hearing effortlessly segregate one sound source from another. Our laboratory is investigating the neural basis of this perceptual feat, often called the "cocktail party effect", using the barn owl as an animal model. The barn owl, renowned for its ability to localize sounds and its spatiotopic representation of auditory space, is an established model for spatial hearing. Here, we briefly review the neural basis of sound-localization of a single sound source in an anechoic environment and then generalize the ideas developed therein to cases in which there are multiple, concomitant sound sources and acoustical reflection.

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Responses of Auditory Cortical Neurons to Pairs of Sounds: Correlates of Fusion and Localization

Cited by 41 publications

References 58 publications

Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

Influence of Sound Source Location on the Behavior and Physiology of the Precedence Effect in Cats

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

Object localization in cluttered acoustical environments

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