Natural ITD statistics predict human auditory spatial perception

A neural code adapted to the statistical structure of sensory cues may optimize perception. We investigated whether interaural time difference (ITD) statistics inherent in natural acoustic scenes are parameters determining spatial discriminability. The natural ITD rate of change across azimuth (ITDrc) and ITD variability over time (ITDv) were combined in a Fisher information statistic for assessing the amount of azimuthal information conveyed by this sensory cue. We hypothesized that natural ITD statistics drive the neural code for ITD and thus influence spatial perception. Human spatial discriminability and spatial novelty detection of sounds with invariant statistics correlated with natural ITD statistics. The lack of natural statistics in the stimuli suggests that this correlation results from natural statistics driving the neural code. Additionally, the density distribution of ITD tuning matching natural statistics is consistent with classic models of ITD coding and can explain the ITD tuning distribution observed in the mammalian brainstem.Impact statementHuman brain has incorporated natural statistics of spatial cues to the neural code supporting perception of sound location.Major subject areaNeuroscience;Research organismHuman;

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Natural ITD statistics predict human auditory spatial perception

eLife ◽

10.7554/elife.51927 ◽

2020 ◽

Vol 9 ◽

Author(s):

Rodrigo Pavão ◽

Elyse S Sussman ◽

Brian J Fischer ◽

José L Peña

Keyword(s):

Spatial Perception ◽

Novelty Detection ◽

Interaural Time Difference ◽

Neural Code ◽

Rate Of Change ◽

Statistical Structure ◽

Spatial Novelty ◽

Sensory Cue ◽

Information Statistic ◽

Invariant Statistics

A neural code adapted to the statistical structure of sensory cues may optimize perception. We investigated whether interaural time difference (ITD) statistics inherent in natural acoustic scenes are parameters determining spatial discriminability. The natural ITD rate of change across azimuth (ITDrc) and ITD variability over time (ITDv) were combined in a Fisher information statistic to assess the amount of azimuthal information conveyed by this sensory cue. We hypothesized that natural ITD statistics underlie the neural code for ITD and thus influence spatial perception. To test this hypothesis, sounds with invariant statistics were presented to measure human spatial discriminability and spatial novelty detection. Human auditory spatial perception showed correlation with natural ITD statistics, supporting our hypothesis. Further analysis showed that these results are consistent with classic models of ITD coding and can explain the ITD tuning distribution observed in the mammalian brainstem.

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Reduced temporal processing in older, normal-hearing listeners evident from electrophysiological responses to shifts in interaural time difference

Journal of Neurophysiology ◽

10.1152/jn.00560.2016 ◽

2016 ◽

Vol 116 (6) ◽

pp. 2720-2729 ◽

Cited By ~ 15

Author(s):

Erol J. Ozmeral ◽

David A. Eddins ◽

Ann C. Eddins

Keyword(s):

Cognitive Processing ◽

Temporal Processing ◽

Spatial Perception ◽

Interaural Time Difference ◽

Relative Activity ◽

Time Difference ◽

Asymmetric Distribution ◽

Neural Synchrony ◽

Spatial Cues ◽

Age Related

Previous electrophysiological studies of interaural time difference (ITD) processing have demonstrated that ITDs are represented by a nontopographic population rate code. Rather than narrow tuning to ITDs, neural channels have broad tuning to ITDs in either the left or right auditory hemifield, and the relative activity between the channels determines the perceived lateralization of the sound. With advancing age, spatial perception weakens and poor temporal processing contributes to declining spatial acuity. At present, it is unclear whether age-related temporal processing deficits are due to poor inhibitory controls in the auditory system or degraded neural synchrony at the periphery. Cortical processing of spatial cues based on a hemifield code are susceptible to potential age-related physiological changes. We consider two distinct predictions of age-related changes to ITD sensitivity: declines in inhibitory mechanisms would lead to increased excitation and medial shifts to rate-azimuth functions, whereas a general reduction in neural synchrony would lead to reduced excitation and shallower slopes in the rate-azimuth function. The current study tested these possibilities by measuring an evoked response to ITD shifts in a narrow-band noise. Results were more in line with the latter outcome, both from measured latencies and amplitudes of the global field potentials and source-localized waveforms in the left and right auditory cortices. The measured responses for older listeners also tended to have reduced asymmetric distribution of activity in response to ITD shifts, which is consistent with other sensory and cognitive processing models of aging.

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The neural code for interaural time difference in human auditory cortex

The Journal of the Acoustical Society of America ◽

10.1121/1.3290744 ◽

2010 ◽

Vol 127 (2) ◽

pp. EL60-EL65 ◽

Cited By ~ 37

Author(s):

Nelli H. Salminen ◽

Hannu Tiitinen ◽

Santeri Yrttiaho ◽

Patrick J. C. May

Keyword(s):

Auditory Cortex ◽

Interaural Time Difference ◽

Neural Code ◽

Time Difference ◽

Human Auditory Cortex

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Adaptive plasticity of the auditory space map in the optic tectum of adult and baby barn owls in response to external ear modification

Journal of Neurophysiology ◽

10.1152/jn.1994.71.1.79 ◽

1994 ◽

Vol 71 (1) ◽

pp. 79-94 ◽

Cited By ~ 30

Author(s):

E. I. Knudsen ◽

S. D. Esterly ◽

J. F. Olsen

Keyword(s):

Spatial Pattern ◽

Optic Tectum ◽

Interaural Time Difference ◽

Rate Of Change ◽

Adaptive Plasticity ◽

Interaural Level Difference ◽

External Ear ◽

Site Location ◽

Physiological Range ◽

Barn Owls

1. This study demonstrates the influence of experience on the establishment and maintenance of the auditory map of space in the optic tectum of the barn owl. Auditory experience was altered either by preventing the structures of the external ears (the facial ruff and preaural flaps) from appearing in baby barn owls (baby ruff-cut owls) or by removing these structures in adults (adult ruff-cut owls). These structures shape the binaural cues used for localizing sounds in both the horizontal and vertical dimensions. 2. The acoustic effects of removing the external ear structures were measured using probe tube microphones placed in the ear canals. In both baby and adult ruff-cut owls, the spatial pattern of binaural localization cues was dramatically different from normal: interaural level difference (ILD) changed with azimuth instead of with elevation, the rate of change of ILD across space was decreased relative to normal, and the rate of change of interaural time difference (ITD) across frontal space was increased relative to normal. 3. The neurophysiological representations of ITD and ILD in the optic tectum were measured before and > or = 3 mo after ruff removal in adults and beginning at 4.5 months of age in baby ruff-cut owls. Multiunit tuning to ITD and to ILD was measured using dichotic stimulation in ketamine-anesthetized owls. The tectal maps of ITD and ILD were reconstructed using visual receptive field location as a marker for recording site location in the optic tectum. 4. Adjustment of the tectal map of ITD to the altered spatial pattern of acoustic ITD was essentially complete in adults as well as in baby ruff-cut owls. This adjustment changed the magnification of ITD across the tectum, with resultant changes in ITD tuning at individual tectal sites of up to approximately 25 microseconds (approximately 5% of the physiological range) relative to normal values. 5. Adaptation of the tectal ILD map to the ruff-cut spatial pattern of acoustic ILD was substantial but clearly incomplete in both adult and baby ruff-cut owls. Although changes of up to approximately 15 dB (approximately 47% of the physiological range) relative to normal tuning were observed at certain tectal sites, the topography of the ILD map was always intermediate between normal and that predicted by the ruff-cut spatial pattern of acoustic ILD.(ABSTRACT TRUNCATED AT 400 WORDS)

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Depth Modulation: Composing motion in immersive audiovisual spaces

Organised Sound ◽

10.1017/s1355771812000088 ◽

2012 ◽

Vol 17 (2) ◽

pp. 156-162

Author(s):

Ewa Trębacz

Keyword(s):

Spatial Perception ◽

Three Dimensional ◽

Electroacoustic Music ◽

Continuous Change ◽

Perfect Field ◽

Spatial Cues ◽

Depth Cues ◽

Visual Music ◽

Surrounding Environment ◽

Narrative Storylines

The field of electroacoustic music has witnessed years of extensive exploration of aural spatial perception and an abundance of spatialisation techniques. Today the growing ubiquity of visual 3D technologies gives artists a similar opportunity in the realm of visual music. With the use of stereoscopic video we now have the ability to compose individual depth cues independently. The process of continuous change of the perceived depth of the audiovisual space over time is being referred to as depth modulation, and can only be fully appreciated through motion.What can be achieved through the separation and manipulation of visual and sonic spatial cues? What can we learn about the way we perceive space if the basic components building our understanding of the surrounding environment are artificially split and re-arranged?Visual music appears to be a perfect field for such experimentation. Strata of visual and aural depth cues can be used to create audiovisual counterpoints in three-dimensional spaces. The choice of abstract imagery and the lack of obvious narrative storylines allow us to focus our perception on the evolution of the immersive audiovisual space itself. A new language of an immersive audiovisual medium should emerge as a delicate, ever-changing balance between all previously separated and altered components.

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Judgments of Object Size and Distance across Different Virtual Reality Environments: A Preliminary Study

Applied Sciences ◽

10.3390/app112311510 ◽

2021 ◽

Vol 11 (23) ◽

pp. 11510

Author(s):

Hannah Park ◽

Nafiseh Faghihi ◽

Manish Dixit ◽

Jyotsna Vaid ◽

Ann McNamara

Keyword(s):

Virtual Reality ◽

Visual Cues ◽

Spatial Perception ◽

Outer Space ◽

Extreme Environments ◽

Depth Estimation ◽

Size Perception ◽

Spatial Cues ◽

Total Absence ◽

Preliminary Study

Emerging technologies offer the potential to expand the domain of the future workforce to extreme environments, such as outer space and alien terrains. To understand how humans navigate in such environments that lack familiar spatial cues this study examined spatial perception in three types of environments. The environments were simulated using virtual reality. We examined participants’ ability to estimate the size and distance of stimuli under conditions of minimal, moderate, or maximum visual cues, corresponding to an environment simulating outer space, an alien terrain, or a typical cityscape, respectively. The findings show underestimation of distance in both the maximum and the minimum visual cue environment but a tendency for overestimation of distance in the moderate environment. We further observed that depth estimation was substantially better in the minimum environment than in the other two environments. However, estimation of height was more accurate in the environment with maximum cues (cityscape) than the environment with minimum cues (outer space). More generally, our results suggest that familiar visual cues facilitated better estimation of size and distance than unfamiliar cues. In fact, the presence of unfamiliar, and perhaps misleading visual cues (characterizing the alien terrain environment), was more disruptive than an environment with a total absence of visual cues for distance and size perception. The findings have implications for training workers to better adapt to extreme environments.

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Spatial Stimulus Cue Information Supplying Auditory Saltation

Perception ◽

10.1068/p3293 ◽

2002 ◽

Vol 31 (7) ◽

pp. 875-885 ◽

Cited By ~ 11

Author(s):

Dennis P Phillips ◽

Susan E Hall ◽

Susan E Boehnke ◽

Leanna E D Rutherford

Keyword(s):

Spatial Perception ◽

Interaural Time Difference ◽

Free Field ◽

Spatial Location ◽

Interaural Level Difference ◽

Sound Sources ◽

Interaural Time Differences ◽

Spatial Stimulus ◽

Click Train ◽

Interaural Level Differences

Auditory saltation is a misperception of the spatial location of repetitive, transient stimuli. It arises when clicks at one location are followed in perfect temporal cadence by identical clicks at a second location. This report describes two psychophysical experiments designed to examine the sensitivity of auditory saltation to different stimulus cues for auditory spatial perception. Experiment 1 was a dichotic study in which six different six-click train stimuli were used to generate the saltation effect. Clicks lateralised by using interaural time differences and clicks lateralised by using interaural level differences produced equivalent saltation effects, confirming an earlier finding. Switching the stimulus cue from an interaural time difference to an interaural level difference (or the reverse) in mid train was inconsequential to the saltation illusion. Experiment 2 was a free-field study in which subjects rated the illusory motion generated by clicks emitted from two sound sources symmetrically disposed around the interaural axis, ie on the same cone of confusion in the auditory hemifield opposite one ear. Stimuli in such positions produce spatial location judgments that are based more heavily on monaural spectral information than on binaural computations. The free-field stimuli produced robust saltation. The data from both experiments are consistent with the view that auditory saltation can emerge from spatial processing, irrespective of the stimulus cue information used to determine click laterality or location.

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Weak neural signatures of spatial selective auditory attention in hearing-impaired listeners

10.1101/675595 ◽

2019 ◽

Author(s):

Lia M. Bonacci ◽

Lengshi Dai ◽

Barbara G. Shinn-Cunningham

Keyword(s):

Spatial Attention ◽

Interaural Time Difference ◽

Hearing Impaired ◽

Auditory Attention ◽

Focused Attention ◽

Alpha Power ◽

Spatial Difference ◽

Neural Responses ◽

Spatial Cues ◽

Spatial Features

AbstractSpatial attention may be used to select target speech in one location while suppressing irrelevant speech in another. However, if perceptual resolution of spatial cues is weak, spatially focused attention may work poorly, leading to difficulty communicating in noisy settings. In electroencephalography (EEG), the distribution of alpha (8–14 Hz) power over parietal sensors reflects the spatial focus of attention (Banerjee et al., 2011; Foxe and Snyder, 2011). If spatial attention is degraded, however, alpha may not be modulated across parietal sensors. A previously published behavioral and EEG study found that, compared to normal-hearing (NH) listeners, hearing-impaired (HI) listeners often had higher interaural time difference (ITD) thresholds, worse performance when asked to report the content of an acoustic stream from a particular location, and weaker attentional modulation of neural responses evoked by sounds in a mixture (Dai et al., 2018). This study explored whether these same HI listeners also showed weaker alpha lateralization during the previously reported task. In NH listeners, hemispheric parietal alpha power was greater when the ipsilateral location was attended; this lateralization was stronger when competing melodies were separated by a larger spatial difference. In HI listeners, however, alpha was not lateralized across parietal sensors, consistent with a degraded ability to use spatial features to selectively attend.

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