Parallel Emergence of Spatial Tuning and Echo Suppression in the Auditory Midbrain? Focus on “A Neuronal Correlate of the Precedence Effect Is Associated With Spatial Selectivity in the Barn Owl's Auditory Midbrain”

2004 ◽  
Vol 92 (4) ◽  
pp. 1965-1966 ◽  
Author(s):  
G. Christopher Stecker
Keyword(s):  
Precedence Effect ◽  
Auditory Midbrain ◽  
Spatial Selectivity ◽  
Neuronal Correlate ◽  
Spatial Tuning ◽  
Echo Suppression

A Neuronal Correlate of the Precedence Effect Is Associated With Spatial Selectivity in the Barn Owl's Auditory Midbrain

2004 ◽  
Vol 92 (4) ◽  
pp. 2051-2070 ◽  
Author(s):  
Matthew W. Spitzer ◽  
Avinash D. S. Bala ◽  
Terry T. Takahashi
Keyword(s):  
Receptive Field ◽  
Inferior Colliculus ◽  
Sound Localization ◽  
Auditory Processing ◽  
Precedence Effect ◽  
Auditory Midbrain ◽  
Spatial Selectivity ◽  
Neuronal Correlate ◽  
Spatial Tuning ◽  
Underlying Mechanisms

Sound localization in echoic conditions depends on a precedence effect (PE), in which the first arriving sound dominates the perceived location of later reflections. Previous studies have demonstrated neurophysiological correlates of the PE in several species, but the underlying mechanisms remain unknown. The present study documents responses of space-specific neurons in the barn owl's inferior colliculus (IC) to stimuli simulating direct sounds and reflections that overlap in time at the listener's ears. Responses to 100-ms noises with lead-lag delays from 1 to 100 ms were recorded from neurons in the space-mapped subdivisions of IC in anesthetized owls (N2O/isofluorane). Responses to a target located at a unit's best location were usually suppressed by a masker located outside the excitatory portion of the spatial receptive field. The least spatially selective units exhibited temporally symmetric effects, in that the amount of suppression was the same whether the masker led or lagged. Such effects mirror the alteration of localization cues caused by acoustic superposition of leading and lagging sounds. In more spatially selective units, the suppression was often temporally asymmetric, being more pronounced when the masker led. The masker often evoked small changes in spatial tuning that were not related to the magnitude of suppressive effects. The association of temporally asymmetric suppression with spatial selectivity suggests that this property emerges within IC, and not at earlier stages of auditory processing. Asymmetric suppression reduces the ability of highly spatially selective neurons to encode the location of lagging sounds, providing a possible basis for the PE.

scholarly journals The Binaural Interaction Component of the Auditory Brainstem Response Under Precedence Effect Conditions

2020 ◽  
Vol 24 ◽  
pp. 233121652094613
Author(s):  
Kelly Dean ◽  
John H. Grose
Keyword(s):  
Auditory Brainstem Response ◽  
Interaural Time Difference ◽  
Auditory Brainstem ◽  
Auditory Brainstem Responses ◽  
Precedence Effect ◽  
Binaural Processing ◽  
Binaural Interaction ◽  
Brainstem Response ◽  
Echo Suppression ◽  
Interaction Component

The purpose of this study was to measure the binaural interaction component (BIC) derived from click-evoked auditory brainstem responses (ABRs) using stimuli configured to elicit the Precedence Effect. The hypothesis was that the contribution of binaural processing to echo suppression can be evidenced by a diminished or absent BIC associated with the echo. Ten normal-hearing young adults provided ABRs generated by sequences of click pairs. Results showed that BICs elicited by diotic clicks in isolation were obliterated when those diotic clicks were preceded by a click pair having an interaural time difference of 400 µs and where the interclick interval was 8.4 ms. The presence of the leading click pair increased the latency of the ABR generated by the lagging diotic click pair but did not decrease its amplitude. The results were interpreted as indicating a contribution of binaural processing at the level of the brainstem to echo suppression, at least for the conditions tested here.

Is There a Hearing Aid for the Thinking Person?

2010 ◽  
Vol 21 (09) ◽  
pp. 594-600 ◽  
Author(s):  
Ervin R. Hafter
Keyword(s):  
Hearing Aids ◽  
Verbal Memory ◽  
Hearing Aid ◽  
Reaction Times ◽  
Precedence Effect ◽  
Auditory Prosthesis ◽  
Speech In Noise ◽  
Improved Performance ◽  
Echo Suppression ◽  
Listening Strategies

Background: The history of auditory prosthesis has generally concentrated on bottom-up processing, that is, on audibility. However, a growing interest in top-down processing has focused on correlations between success with a hearing aid and such higher order processing as the patient's intelligence, problem solving and language skills, and the perceived effort of day-to-day listening. Purpose: Examination of two cases of cognitive effects in hearing that illustrate less-often-studied issues: (1) Individual subjects in a study use different listening strategies, a fact that, if not known to the experimenter, can lead to errors in interpretation; (2) A measure of shared attention can point to otherwise unknown functional effects of an algorithm used in hearing aids. Research design: In the two examples described above: (1) Patients with cochlear implants served in a study of the binaural precedence effect, that is, echo suppression. (2) Individuals identifying speech-in-noise benefit from noise reduction (NR) when the criterion was improved performance in simultaneous tests of verbal memory or visual reaction times. Conclusions: Studies of hearing impairment, either in the laboratory or in a fitting session, should include study of the complex stimuli that make up the natural environment, conditions where the thinking auditory brain adopts strategies for dealing with large amounts of input data. In addition to well-known factors that must be included in communication, such things as familiarity, syntax, and semantics, the work here shows that strategic listening can affect even how we deal with seemingly simpler requirements, localizing sounds in a reverberant auditory scene and listening for speech in noise when busy with other cognitive tasks.

scholarly journals Evidence for a neural source of the precedence effect in sound localization

2015 ◽  
Vol 114 (5) ◽  
pp. 2991-3001 ◽  
Author(s):  
Andrew D. Brown ◽  
Heath G. Jones ◽  
Alan Kan ◽  
Tanvi Thakkar ◽  
G. Christopher Stecker ◽  
...  
Keyword(s):  
Sound Localization ◽  
Normal Hearing ◽  
Nerve Fibers ◽  
Precedence Effect ◽  
Auditory Midbrain ◽  
Cochlear Function ◽  
Sound Sources ◽  
Human Patient ◽  
Bilateral Cochlear Implants ◽  
Reverberant Environments

Normal-hearing human listeners and a variety of studied animal species localize sound sources accurately in reverberant environments by responding to the directional cues carried by the first-arriving sound rather than spurious cues carried by later-arriving reflections, which are not perceived discretely. This phenomenon is known as the precedence effect (PE) in sound localization. Despite decades of study, the biological basis of the PE remains unclear. Though the PE was once widely attributed to central processes such as synaptic inhibition in the auditory midbrain, a more recent hypothesis holds that the PE may arise essentially as a by-product of normal cochlear function. Here we evaluated the PE in a unique human patient population with demonstrated sensitivity to binaural information but without functional cochleae. Users of bilateral cochlear implants (CIs) were tested in a psychophysical task that assessed the number and location(s) of auditory images perceived for simulated source-echo (lead-lag) stimuli. A parallel experiment was conducted in a group of normal-hearing (NH) listeners. Key findings were as follows: 1) Subjects in both groups exhibited lead-lag fusion. 2) Fusion was marginally weaker in CI users than in NH listeners but could be augmented by systematically attenuating the amplitude of the lag stimulus to coarsely simulate adaptation observed in acoustically stimulated auditory nerve fibers. 3) Dominance of the lead in localization varied substantially among both NH and CI subjects but was evident in both groups. Taken together, data suggest that aspects of the PE can be elicited in CI users, who lack functional cochleae, thus suggesting that neural mechanisms are sufficient to produce the PE.

scholarly journals Echo suppression and discrimination suppression aspects of the precedence effect

1997 ◽  
Vol 59 (7) ◽  
pp. 1108-1117 ◽  
Author(s):  
Xuefeng Yang ◽  
D. Wesley Grantham
Keyword(s):  
Precedence Effect ◽  
Echo Suppression

scholarly journals Echolocation versus echo suppression in humans

2013 ◽  
Vol 280 (1769) ◽  
pp. 20131428 ◽  
Author(s):  
Ludwig Wallmeier ◽  
Nikodemus Geßele ◽  
Lutz Wiegrebe
Keyword(s):  
Sound Source ◽  
Spatial Information ◽  
Precedence Effect ◽  
Sound Sources ◽  
Source Discrimination ◽  
Additional Control ◽  
Acoustic Space ◽  
Echo Suppression ◽  
Listening Experiment ◽  
Blind Humans

Several studies have shown that blind humans can gather spatial information through echolocation. However, when localizing sound sources, the precedence effect suppresses spatial information of echoes, and thereby conflicts with effective echolocation. This study investigates the interaction of echolocation and echo suppression in terms of discrimination suppression in virtual acoustic space. In the ‘Listening’ experiment, sighted subjects discriminated between positions of a single sound source, the leading or the lagging of two sources, respectively. In the ‘Echolocation’ experiment, the sources were replaced by reflectors. Here, the same subjects evaluated echoes generated in real time from self-produced vocalizations and thereby discriminated between positions of a single reflector, the leading or the lagging of two reflectors, respectively. Two key results were observed. First, sighted subjects can learn to discriminate positions of reflective surfaces echo-acoustically with accuracy comparable to sound source discrimination. Second, in the Listening experiment, the presence of the leading source affected discrimination of lagging sources much more than vice versa. In the Echolocation experiment, however, the presence of both the lead and the lag strongly affected discrimination. These data show that the classically described asymmetry in the perception of leading and lagging sounds is strongly diminished in an echolocation task. Additional control experiments showed that the effect is owing to both the direct sound of the vocalization that precedes the echoes and owing to the fact that the subjects actively vocalize in the echolocation task.

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