Reweighting of Binaural Localization Cues Induced by Lateralization Training

Klingel, Maike; Kopčo, Norbert; Laback, Bernhard

doi:10.1007/s10162-021-00800-8

Cited by 13 publications

(28 citation statements)

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“…Furthermore, recent studies have demonstrated that lateralization training can lead to a reweighting of binaural cues in normal hearing listeners (Kumpik et al 2019; Klingel et al 2021) and biCI users (Klingel and Laback 2022), such that the listeners rely more or less heavily on ILDs or ITDs respectively depending on which cue is more reliable or informative. This could be relevant for CI listeners, as they could similarly down-weight ITD cues if the ongoing stimulation with clinical processors does not transmit reliable, informative ITDs which would thus encourage a reliance exclusively on ILDs to the detriment of ITDs.…”

Section: Discussionmentioning

confidence: 99%

Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps

Buck

Buchholz

Schnupp

et al. 2022

Preprint

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Spatial hearing remains one of the major challenges for bilateral cochlear implant (biCI) users, and early deaf patients in particular are often completely insensitive to interaural time differences (ITDs) delivered through biCIs. One popular theory held is that this may be due to a lack of early binaural experience. However, previously we have shown that neonatally deafened rats fitted with biCIs in adulthood quickly learn to discriminate ITDs as well as their normal hearing litter mates (Rosskothen-Kuhl et al. 2021), and perform orders of magnitude better than human biCI users. Our unique behaving biCI rat model allows us to investigate other possible limiting factors of prosthetic binaural hearing, such as the effect of stimulus pulse rate and envelope shape. Previous work has indicated that ITD sensitivity may decline substantially at the high pulse rates often used in clinical practice. We therefore measured behavioral ITD thresholds in neonatally deafened, adult implanted biCI rats to pulse trains of 50, 300, 900 and 1800 pulses per second (pps), with either rectangular or Hanning window envelopes. Our rats exhibited very high sensitivity to ITDs at pulse rates up to 900 pps for both envelope shapes, a pulse rate commonly used in clinical practice. However, ITD sensitivity declined to near zero at 1800 pps, for both Hanning and rectangular windowed pulse trains. Current clinical cochlear implant (CI) processors are often set to pulse rates ≥900 pps, but ITD sensitivity in human CI listeners is often reported to decline sharply above ~300 pps. Our results suggest that the relatively poor ITD sensitivity seen at >300 pps in human CI users may not reflect the hard upper limit of biCI ITD performance in the mammalian auditory pathway. Perhaps with training or better CI strategies good binaural hearing may be achievable at pulse rates high enough to allow good sampling of speech envelopes while delivering usable ITDs.

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Section: Discussionmentioning

confidence: 99%

Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps

Buck

Buchholz

Schnupp

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“… Klingel et al (2020) also observed an increase in ILD weighting after participants received response feedback consistent with the ILDs of a mid-frequency (2–4 kHz) narrow-band noise stimulus in an auditory discrimination task, but did not test a group receiving feedback consistent with the ITDs. Finally, Klingel et al (2021) observed a comparably strong increase in either the ITD or the ILD weighting of the same 2–4-kHz noise stimulus, depending on which cue was visually reinforced during a lateralization task in a virtual audio-visual environment.…”

Section: Introductionmentioning

confidence: 88%

“…The aim of this experiment was to test whether binaural-cue weights, measured similarly to Macpherson and Middlebrooks (2002) , will show gradual weight changes across different frequency regions or whether they will show divergence for the lowest and highest frequency bands but constant weights in between, similar to the results reported by Ahrens et al (2020) . We further investigated whether binaural-cue reweighting can be induced for different frequency regions using the paradigm of Klingel et al . (2021 ; see description of methods below).…”

Section: Methodsmentioning

confidence: 99%

“…We chose the low and high bands for training to test for reweighting potential in frequency regions where one of the cues clearly dominates. The mid-high band was chosen because it was close in center frequency to the stimuli used in Klingel et al . (2021) , for which both ITD and ILD reweighting was shown.…”

Section: Methodsmentioning

confidence: 99%

“…In addition to frequency, the binaural-cue weighting is influenced by other stimulus properties such as the overall intensity ( David et al, 1959 ; Deatherage & Hirsh, 1959 ), the inter-click interval of click trains ( Stecker, 2010 ), or the presence of reverberation ( Rakerd & Hartmann, 2010 ) and shows substantial variation across listeners ( Klingel et al, 2021 ; Klingel et al, 2020 ; Macpherson & Middlebrooks, 2002 ). Such a dependence on stimulus, environmental, and personal properties is not surprising, given that listeners adapt their processing of sound localization cues when exposed to cue alterations (see Carlile, 2014 , for a review).…”

Section: Introductionmentioning

confidence: 99%

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Binaural-cue Weighting and Training-Induced Reweighting Across Frequencies

Klingel

Laback

2022

Trends in Hearing

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During sound lateralization, the information provided by interaural differences in time (ITD) and level (ILD) is weighted, with ITDs and ILDs dominating for low and high frequencies, respectively. For mid frequencies, the weighting between these binaural cues can be changed via training. The present study investigated whether binaural-cue weights change gradually with increasing frequency region, whether they can be changed in various frequency regions, and whether such binaural-cue reweighting generalizes to untrained frequencies. In two experiments, a total of 39 participants lateralized 500-ms, 1/3-octave-wide noise bursts containing various ITD/ILD combinations in a virtual audio-visual environment. Binaural-cue weights were measured before and after a 2-session training in which, depending on the group, either ITDs or ILDs were visually reinforced. In experiment 1, four frequency bands (centered at 1000, 1587, 2520, and 4000 Hz) and a multiband stimulus comprising all four bands were presented during weight measurements. During training, only the 1000-, 2520-, and 4000-Hz bands were presented. In experiment 2, the weight measurements only included the two mid-frequency bands, while the training only included the 1587-Hz band. ILD weights increased gradually from low- to high-frequency bands. When ILDs were reinforced during training, they increased for the 4000- (experiment 1) and 2520-Hz band (experiment 2). When ITDs were reinforced, ITD weights increased only for the 1587-Hz band (at specific azimuths). This suggests that ILD reweighting requires high, and ITD reweighting requires low frequencies without including frequency regions providing fine-structure ITD cues. The changes in binaural-cue weights were independent of the trained bands, suggesting some generalization of binaural-cue reweighting.

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Reweighting of Binaural Localization Cues in Bilateral Cochlear-Implant Listeners

Klingel

Laback

2021

JARO

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Normal-hearing (NH) listeners rely on two binaural cues, the interaural time (ITD) and level difference (ILD), for azimuthal sound localization. Cochlear-implant (CI) listeners, however, rely almost entirely on ILDs. One reason is that present-day clinical CI stimulation strategies do not convey salient ITD cues. But even when presenting ITDs under optimal conditions using a research interface, ITD sensitivity is lower in CI compared to NH listeners. Since it has recently been shown that NH listeners change their ITD/ILD weighting when only one of the cues is consistent with visual information, such reweighting might add to CI listeners’ low perceptual contribution of ITDs, given their daily exposure to reliable ILDs but unreliable ITDs. Six bilateral CI listeners completed a multi-day lateralization training visually reinforcing ITDs, flanked by a pre- and post-measurement of ITD/ILD weights without visual reinforcement. Using direct electric stimulation, we presented 100- and 300-pps pulse trains at a single interaurally place-matched electrode pair, conveying ITDs and ILDs in various spatially consistent and inconsistent combinations. The listeners’ task was to lateralize the stimuli in a virtual environment. Additionally, ITD and ILD thresholds were measured before and after training. For 100-pps stimuli, the lateralization training increased the contribution of ITDs slightly, but significantly. Thresholds were neither affected by the training nor correlated with weights. For 300-pps stimuli, ITD weights were lower and ITD thresholds larger, but there was no effect of training. On average across test sessions, adding azimuth-dependent ITDs to stimuli containing ILDs increased the extent of lateralization for both 100- and 300-pps stimuli. The results suggest that low-rate ITD cues, robustly encoded with future CI systems, may be better exploitable for sound localization after increasing their perceptual weight via training.

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Reweighting of Binaural Localization Cues Induced by Lateralization Training

Cited by 13 publications

References 50 publications

Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps

Interaural time difference sensitivity under binaural cochlear implant stimulation persists at high pulse rates up to 900 pps

Binaural-cue Weighting and Training-Induced Reweighting Across Frequencies

Reweighting of Binaural Localization Cues in Bilateral Cochlear-Implant Listeners

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