Effects of Reference Interaural Time and Intensity Differences on Binaural Performance in Listeners with Normal and Impaired Hearing

Koehnke, Janet; Cp, Culotta; Ml, Hawley; Hs, Colburn

doi:10.1097/00003446-199508000-00001

Cited by 62 publications

(86 citation statements)

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“…1 Upper Right). The pretest thresholds of both groups were within the range previously reported for naive or briefly trained listeners (25,26). Here, the ITD thresholds did not differ significantly between the trained and control listeners on either the pretest (t 22 ϭ 1.85, P ϭ 0.078) or the posttest (t 22 ϭ Ϫ0.76, P ϭ 0.458).…”

Section: Resultssupporting

confidence: 81%

“…1 Upper Left), control listeners improved significantly between the pre-and posttest in the trained condition of ILD 0 dB at 4 kHz (t 15 ϭ 3.04, P ϭ 0.008), but ILD-trained listeners improved more than controls. Mean thresholds did not differ significantly between groups on the pretest (t 22 ϭ 1.67, P ϭ 0.109), and were at the high end of the range previously reported for naive or briefly trained listeners (25)(26)(27). However, thresholds were significantly lower for trained than control listeners on the posttest (t 22 ϭ Ϫ3.03, P ϭ 0.006).…”

Section: Resultsmentioning

confidence: 50%

See 1 more Smart Citation

Different patterns of human discrimination learning for two interaural cues to sound-source location

Wright

Fitzgerald²

2001

Proc. Natl. Acad. Sci. U.S.A.

146

144

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Two of the primary cues used to localize the sources of sounds are interaural level differences (ILDs) and interaural time differences (ITDs). We conducted two experiments to explore how practice affects the human discrimination of values of ILDs and ongoing ITDs presented over headphones. We measured discrimination thresholds of 13 to 32 naive listeners in a variety of conditions during a pretest and again, 2 weeks later, during a posttest. Between those two tests, we trained a subset of listeners 1 h per day for 9 days on a single ILD or ITD condition. Listeners improved on both ILD and ITD discrimination. Improvement was initially rapid for both cue types and appeared to generalize broadly across conditions, indicating conceptual or procedural learning. A subsequent slower-improvement stage, which occurred solely for the ILD cue, only affected conditions with the trained stimulus frequency, suggesting that stimulus processing had fundamentally changed. These different learning patterns indicate that practice affects the attention to, or low-level encoding of, ILDs and ITDs at sites at which the two cue types are processed separately. Thus, these data reveal differences in the effect of practice on ILD and ITD discrimination, and provide insight into the encoding of these two cues to sound-source location in humans.A listener who determines the position of a singing bird concealed among tree leaves, a jet passing overhead hidden by clouds, or a car approaching from behind, does so by using several auditory cues to the location of sound sources. Here we report the results of two investigations into how practice influences the ability of human listeners to discriminate small differences in each of two of these cues, interaural level differences (ILDs) and interaural time differences (ITDs).In humans, the horizontal location, or azimuth, of sound sources is computed from differences in the information that arrives at the two ears. At frequencies above about 1.5 kHz, listeners determine sound azimuth primarily from sensitivity to differences in sound level at the two ears. These interaural level differences occur because the head forms a sound barrier between the two ears, so sounds are attenuated at the ear farthest from the source relative to the ear nearest to the source (1, 2). At frequencies below about 1.5 kHz, listeners determine sound azimuth primarily from sensitivity to differences in the arrival time of the sound at the two ears. These interaural time differences arise because there is distance between the two ears, so sounds reach the ear nearest to the sound source first and the other ear later (1, 2). For sound durations greater than about 150 ms, listeners are far more sensitive to differences at the two ears in the ongoing fine time structure of the sound than in the onset time of the sound (3, 4). These ongoing time differences are equivalent to interaural phase differences (IPDs) for tonal stimuli, but will be referred to as ITDs in this paper.There have been many investigations into whether huma...

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Section: Resultssupporting

confidence: 81%

Section: Resultsmentioning

confidence: 50%

Different patterns of human discrimination learning for two interaural cues to sound-source location

Wright

Fitzgerald²

2001

Proc. Natl. Acad. Sci. U.S.A.

146

144

View full text Add to dashboard Cite

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“…The relatively large q ref ¼ 1 JNDs would have been more susceptible to measurement noise. Note that previous NH studies have shown weak correlations between ITD JNDs and NoSp or correlation change JNDs for non-vocoded stimuli (Koehnke et al, 1986;Koehnke et al, 1995). Therefore it seems likely that neural degeneration affected CI performance in this study.…”

Section: B Comparisons To Nh Performancementioning

confidence: 58%

“…Studies using constantamplitude pulse trains to measure ITD and ILD sensitivity often center the stimuli to maximize binaural performance (Litovsky et al, 2012) because centered images show the best binaural discrimination performance in NH listeners (Yost and Dye, 1988;Koehnke et al, 1995). Therefore the uncentered images may have decreased performance in the CI listeners, but not in the NH listeners.…”

Section: B Comparisons To Nh Performancementioning

confidence: 99%

Sensitivity to interaural envelope correlation changes in bilateral cochlear-implant users

Goupell

Litovsky

2015

The Journal of the Acoustical Society of America

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Provision of bilateral cochlear implants (CIs) to people who are deaf is partially justified by improved abilities to understand speech in noise when comparing bilateral vs unilateral listening conditions. However, bilateral CI listeners generally show only monaural head shadow with little improvement in speech understanding due to binaural unmasking. Sensitivity to change in interaural envelope correlation, which is related to binaural speech unmasking, was investigated. Bilateral CI users were tested with bilaterally synchronized processors at single, pitch-matched electrode pairs. First, binaural masking level differences (BMLDs) were measured using 1000 pulse-per-second (pps) carriers, yielding BMLDs of 11.1 6 6.5 and 8.5 6 4.2 dB for 10-and 50-Hz bandwidth masking noises, respectively. Second, envelope correlation change just-noticeable differences (JNDs) were measured. Stimuli presented at 1000 pps yielded lower JNDs than those presented at 100 pps. Furthermore, perfectly correlated reference stimuli produced lower JNDs than uncorrelated references, and uncorrelated references generally produced immeasurable JNDs. About 25% of JNDs measured in the CI listeners were in the range of JNDs observed in normal-hearing listeners presented CI simulations. In conclusion, CI listeners can perceive changes in interaural envelope correlation, but the poor performance may be a major limiting factor in binaural unmasking tested to date in realistic listening environments.

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“…However, such errors become more apparent in degraded acoustic environments and situations where visual cues of the sound source are not available. Though a review of the literature has ample of citations on the nature and consequences of spatial acuity deficits [11][12][13][14] , the remediation programs initialized at ameliorating the spatial difficulties are scanty. Some of the notable strides in enhancing spatial acuity have used interaural difference training [15][16][17][18][19][20][21] in remediating errors due to poor spatial processing.…”

Section: Introductionmentioning

confidence: 99%

Virtual Auditory Space Training-Induced Changes of Auditory Spatial Processing in Listeners with Normal Hearing

Nisha

Kumar²

2017

Int Adv Otol

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OBJECTIVE:Localization involves processing of subtle yet highly enriched monaural and binaural spatial cues. Remediation programs aimed at resolving spatial deficits are surprisingly scanty in literature. The present study is designed to explore the changes that occur in the spatial performance of normal-hearing listeners before and after subjecting them to virtual acoustic space (VAS) training paradigm using behavioral and electrophysiological measures. MATERIALS and METHODS:Ten normal-hearing listeners participated in the study, which was conducted in three phases, including a pre-training, training, and post-training phase. At the pre-and post-training phases both behavioral measures of spatial acuity and electrophysiological P300 were administered. The spatial acuity of the participants in the free field and closed field were measured apart from quantifying their binaural processing abilities. The training phase consisted of 5-8 sessions (20 min each) carried out using a hierarchy of graded VAS stimuli. RESULTS:The results obtained from descriptive statistics were indicative of an improvement in all the spatial acuity measures in the post-training phase. Statistically, significant changes were noted in interaural time difference (ITD) and virtual acoustic space identification scores measured in the post-training phase. Effect sizes (r) for all of these measures were substantially large, indicating the clinical relevance of these measures in documenting the impact of training. However, the same was not reflected in P300. CONCLUSION:The training protocol used in the present study on a preliminary basis proves to be effective in normal-hearing listeners, and its implications can be extended to other clinical population as well.

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Effects of Reference Interaural Time and Intensity Differences on Binaural Performance in Listeners with Normal and Impaired Hearing

Cited by 62 publications

References 0 publications

Different patterns of human discrimination learning for two interaural cues to sound-source location

Different patterns of human discrimination learning for two interaural cues to sound-source location

Sensitivity to interaural envelope correlation changes in bilateral cochlear-implant users

Virtual Auditory Space Training-Induced Changes of Auditory Spatial Processing in Listeners with Normal Hearing

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