Gravitoinertial Force Magnitude and Direction Influence Head-Centric Auditory Localization

2001 ◽  
Vol 85 (6) ◽  
pp. 2455-2460 ◽  
Author(s):  
Paul DiZio ◽  
Richard Held ◽  
James R. Lackner ◽  
Barbara Shinn-Cunningham ◽  
Nathaniel Durlach
Keyword(s):  
Sound Localization ◽  
Acoustic Stimulus ◽  
Median Plane ◽  
Broadband Noise ◽  
Auditory Localization ◽  
Slow Rotation ◽  
Angular Deviation ◽  
Midsagittal Plane ◽  
Gravitoinertial Force ◽  
Straight Ahead

We measured the influence of gravitoinertial force (GIF) magnitude and direction on head-centric auditory localization to determine whether a true audiogravic illusion exists. In experiment 1, supine subjects adjusted computer-generated dichotic stimuli until they heard a fused sound straight ahead in the midsagittal plane of the head under a variety of GIF conditions generated in a slow-rotation room. The dichotic stimuli were constructed by convolving broadband noise with head-related transfer function pairs that model the acoustic filtering at the listener's ears. These stimuli give rise to the perception of externally localized sounds. When the GIF was increased from 1 to 2 g and rotated 60° rightward relative to the head and body, subjects on average set an acoustic stimulus 7.3° right of their head's median plane to hear it as straight ahead. When the GIF was doubled and rotated 60° leftward, subjects set the sound 6.8° leftward of baseline values to hear it as centered. In experiment 2, increasing the GIF in the median plane of the supine body to 2 g did not influence auditory localization. In experiment 3, tilts up to 75° of the supine body relative to the normal 1 g GIF led to small shifts, 1–2°, of auditory setting toward the up ear to maintain a head-centered sound localization. These results show that head-centric auditory localization is affected by azimuthal rotation and increase in magnitude of the GIF and demonstrate that an audiogravic illusion exists. Sound localization is shifted in the direction opposite GIF rotation by an amount related to the magnitude of the GIF and its angular deviation relative to the median plane.

Effects of Altering Spectral Cues in Infancy on Horizontal and Vertical Sound Localization by Adult Ferrets

1999 ◽  
Vol 82 (5) ◽  
pp. 2294-2309 ◽  
Author(s):  
Carl H. Parsons ◽  
Richard G. Lanyon ◽  
Jan W. H. Schnupp ◽  
Andrew J. King
Keyword(s):  
Sound Localization ◽  
Horizontal Plane ◽  
Broadband Noise ◽  
Neural Representation ◽  
Localization Task ◽  
Midsagittal Plane ◽  
Relative Localization ◽  
Spectral Cues ◽  
Spectral Localization ◽  
Localization Ability

We investigated the behavioral consequences of removing the pinna and concha of the external ear bilaterally in infancy on the sound localization ability of adult ferrets. Altering spectral cues in this manner has previously been shown to disrupt the development of the neural representation of auditory space in the superior colliculus. Using broadband noise stimuli, we tested pinnae-removed ferrets and normal ferrets in three sound localization tasks. In each case, we found that both groups of animals performed significantly better when longer duration noise bursts were used. In a relative localization task, we measured the acuity with which the ferrets could discriminate between two speakers in the horizontal plane. The speakers were placed symmetrically either around the anterior midline or around a position 45° lateral to the midline. In this task, the pinnae-removed ferrets achieved very similar scores to the normal ferrets. By contrast, in another relative localization task that measured localization ability in the midsagittal plane, pinnae-removed ferrets performed less well than normals. In an absolute localization task, 12 speakers were spaced at 30° intervals in the horizontal plane at the level of the ferrets' ears. Overall, the pinnae-removed ferrets also performed poorly in this task compared with normal ferrets: they made significantly fewer correct responses, larger localization errors and more front-back errors. Both normal and pinnae-removed animals showed an improvement in performance with practice, although the pattern of improvement differed for each group. The largest improvements in localization accuracy were achieved by the pinnae-removed ferrets, particularly at the frontal positions, and their performance eventually approached that of the normal animals. Nevertheless, some intergroup differences were still present. In particular, the pinnae-removed ferrets continued to make significantly more front-back errors than the normals. These deficits can be attributed to differences in the spectral localization cues available to the animals. Acoustical measurements showed that, compared with normal animals, the head-related transfer functions in the horizontal plane were largely ambiguous around the interaural axis and also contained fewer location-dependent features in the midsagittal plane.

scholarly journals Spatial Sensitivity in Field PAF of Cat Auditory Cortex

2003 ◽  
Vol 89 (6) ◽  
pp. 2889-2903 ◽  
Author(s):  
G. Christopher Stecker ◽  
Brian J. Mickey ◽  
Ewan A. Macpherson ◽  
John C. Middlebrooks
Keyword(s):  
Auditory Cortex ◽  
Primary Auditory Cortex ◽  
Median Plane ◽  
Stimulus Location ◽  
Population Coding ◽  
Broadband Noise ◽  
Spatial Sensitivity ◽  
Neural Ensembles ◽  
Artificial Neural Network Ann ◽  
Spike Patterns

We compared the spatial tuning properties of neurons in two fields [primary auditory cortex (A1) and posterior auditory field (PAF)] of cat auditory cortex. Broadband noise bursts of 80-ms duration were presented from loudspeakers throughout 360° in the horizontal plane (azimuth) or 260° in the vertical median plane (elevation). Sound levels varied from 20 to 40 dB above units' thresholds. We recorded neural spike activity simultaneously from 16 sites in field PAF and/or A1 of α-chloralose-anesthetized cats. We assessed spatial sensitivity by examining the dependence of spike count and response latency on stimulus location. In addition, we used an artificial neural network (ANN) to assess the information about stimulus location carried by spike patterns of single units and of ensembles of 2–32 units. The results indicate increased spatial sensitivity, more uniform distributions of preferred locations, and greater tolerance to changes in stimulus intensity among PAF units relative to A1 units. Compared to A1 units, PAF units responded at significantly longer latencies, and latencies varied more strongly with stimulus location. ANN analysis revealed significantly greater information transmission by spike patterns of PAF than A1 units, primarily reflecting the information transmitted by latency variation in PAF. Finally, information rates grew more rapidly with the number of units included in neural ensembles for PAF than A1. The latter finding suggests more accurate population coding of space in PAF, made possible by a more diverse population of neural response types.

Effect of Degree of Separation of Visual-Auditory Stimulus and Eye Position upon Spatial Interaction of Vision and Audition

1976 ◽  
Vol 43 (2) ◽  
pp. 487-493 ◽  
Author(s):  
Robert I. Bermant ◽  
Robert B. Welch
Keyword(s):  
Auditory Stimulus ◽  
Visual Stimulus ◽  
Visual Stimulation ◽  
Spatial Interaction ◽  
Auditory Localization ◽  
Eye Position ◽  
Degree Of Separation ◽  
Straight Ahead ◽  
Over Time

Subjects were exposed to a visual and to an auditory stimulus that differed spatially in laterality of origin. The subjects were observed for visual biasing of auditory localization (the momentary influence of a light on the spatially perceived location of a simultaneously presented sound) and for auditory aftereffect (a change in perceived location of a sound that persists over time and is measured after termination of the visual stimulus). A significant effect of visual stimulation on auditory localization was found only with the measure of bias. Bias was tested as a function of degree of visual-auditory separation (10/20/30°), eye position (straight-ahead/visual stimulus fixation), and position of visual stimulus relative to auditory stimulus (left/right). Only eye position proved statistically significant; straight-ahead eye position induced more bias than did fixation of the visual stimulus.

Cortical Control of Sound Localization in the Cat: Unilateral Cooling Deactivation of 19 Cerebral Areas

2004 ◽  
Vol 92 (3) ◽  
pp. 1625-1643 ◽  
Author(s):  
Shveta Malhotra ◽  
Amee J. Hall ◽  
Stephen G. Lomber
Keyword(s):  
Auditory Cortex ◽  
Sound Localization ◽  
Broad Band ◽  
Acoustic Stimulus ◽  
Anterior Ectosylvian Sulcus ◽  
Area 5 ◽  
Area 6 ◽  
Auditory Field ◽  
Lateral Area ◽  
Medial Area

We examined the ability of mature cats to accurately orient to, and approach, an acoustic stimulus during unilateral reversible cooling deactivation of primary auditory cortex (AI) or 1 of 18 other cerebral loci. After attending to a central visual stimulus, the cats learned to orient to a 100-ms broad-band, white-noise stimulus emitted from a central speaker or 1 of 12 peripheral sites (at 15° intervals) positioned along the horizontal plane. Twenty-eight cats had two to six cryoloops implanted over multiple cerebral loci. Within auditory cortex, unilateral deactivation of AI, the posterior auditory field (PAF) or the anterior ectosylvian sulcus (AES) resulted in orienting deficits throughout the contralateral field. However, unilateral deactivation of the anterior auditory field, the second auditory cortex, or the ventroposterior auditory field resulted in no deficits on the orienting task. In multisensory cortex, unilateral deactivation of neither ventral or dorsal posterior ectosylvian cortices nor anterior or posterior area 7 resulted in any deficits. No deficits were identified during unilateral cooling of the five visual regions flanking auditory or multisensory cortices: posterior or anterior ii suprasylvian sulcus, posterior suprasylvian sulcus or dorsal or ventral posterior suprasylvian gyrus. In motor cortex, we identified contralateral orienting deficits during unilateral cooling of lateral area 5 (5L) or medial area 6 (6m) but not medial area 5 or lateral area 6. In a control visual-orienting task, areas 5L and 6m also yielded deficits to visual stimuli presented in the contralateral field. Thus the sound-localization deficits identified during unilateral deactivation of area 5L or 6m were not unimodal and are most likely the result of motor rather than perceptual impairments. Overall, three regions in auditory cortex (AI, PAF, AES) are critical for accurate sound localization as assessed by orienting.

Effects of a listener’s very slow rotation on sound localization accuracy

2016 ◽  
Vol 140 (4) ◽  
pp. 3269-3269
Author(s):  
Sayaka Tsunokake ◽  
Akio Honda ◽  
Yôiti Suzuki ◽  
Shuichi Sakamoto
Keyword(s):  
Sound Localization ◽  
Slow Rotation ◽  
Localization Accuracy

On sound localization cues in the median plane

1978 ◽  
Vol 64 (S1) ◽  
pp. S35-S35
Author(s):  
M. Morimoto ◽  
K. Nomachi
Keyword(s):  
Sound Localization ◽  
Median Plane

Effect of training in sound localization in the median plane

1975 ◽  
Vol 57 (S1) ◽  
pp. S37-S37
Author(s):  
Y. Yorifuji ◽  
M. Morimoto ◽  
Y. Ando
Keyword(s):  
Sound Localization ◽  
Median Plane

scholarly journals Prediction of Human's Ability in Sound Localization Based on the Statistical Properties of Spike Trains along the Brainstem Auditory Pathway

2014 ◽  
Vol 2014 ◽  
pp. 1-11
Author(s):  
Ram Krips ◽  
Miriam Furst
Keyword(s):  
Time Delay ◽  
Lower Bounds ◽  
Sound Localization ◽  
Human Performance ◽  
Acoustic Stimulus ◽  
Auditory Pathway ◽  
Superior Olivary Complex ◽  
Optimal Estimator ◽  
Interaural Time Delay ◽  
Interaural Level Differences

The minimum audible angle test which is commonly used for evaluating human localization ability depends on interaural time delay, interaural level differences, and spectral information about the acoustic stimulus. These physical properties are estimated at different stages along the brainstem auditory pathway. The interaural time delay is ambiguous at certain frequencies, thus confusion arises as to the source of these frequencies. It is assumed that in a typical minimum audible angle experiment, the brain acts as an unbiased optimal estimator and thus the human performance can be obtained by deriving optimal lower bounds. Two types of lower bounds are tested: the Cramer-Rao and the Barankin. The Cramer-Rao bound only takes into account the approximation of the true direction of the stimulus; the Barankin bound considers other possible directions that arise from the ambiguous phase information. These lower bounds are derived at the output of the auditory nerve and of the superior olivary complex where binaural cues are estimated. An agreement between human experimental data was obtained only when the superior olivary complex was considered and the Barankin lower bound was used. This result suggests that sound localization is estimated by the auditory nuclei using ambiguous binaural information.

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