Computational Models of Binaural Processing

Dietz, Mathias; Ashida, Go

doi:10.1007/978-3-030-57100-9_10

Cited by 6 publications

(5 citation statements)

References 116 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We used modulation depths and neuronal discriminability functions to estimate the performance of binaural processing in the model LSO. While these measures are supposed to reflect the encoding properties of LSO neurons, it is still unknown how the outputs of LSO neurons and other brainstem nuclei are combined in higher auditory areas that "decode" the binaural information to form the perception of sounds (see discussions in [ 7 , 85 , 86 ]). In our population modeling approach, we simply used the rate differences of mirrored LSO neuron pairs and averaged the corresponding discriminability functions within the simulated population ( Fig 7 ).…”

Section: Discussionmentioning

confidence: 99%

Robustness of neuronal tuning to binaural sound localization cues against age-related loss of inhibitory synaptic inputs

2021

Self Cite

View full text Add to dashboard Cite

Sound localization relies on minute differences in the timing and intensity of sound arriving at both ears. Neurons of the lateral superior olive (LSO) in the brainstem process these interaural disparities by precisely detecting excitatory and inhibitory synaptic inputs. Aging generally induces selective loss of inhibitory synaptic transmission along the entire auditory pathways, including the reduction of inhibitory afferents to LSO. Electrophysiological recordings in animals, however, reported only minor functional changes in aged LSO. The perplexing discrepancy between anatomical and physiological observations suggests a role for activity-dependent plasticity that would help neurons retain their binaural tuning function despite loss of inhibitory inputs. To explore this hypothesis, we use a computational model of LSO to investigate mechanisms underlying the observed functional robustness against age-related loss of inhibitory inputs. The LSO model is an integrate-and-fire type enhanced with a small amount of low-voltage activated potassium conductance and driven with (in)homogeneous Poissonian inputs. Without synaptic input loss, model spike rates varied smoothly with interaural time and level differences, replicating empirical tuning properties of LSO. By reducing the number of inhibitory afferents to mimic age-related loss of inhibition, overall spike rates increased, which negatively impacted binaural tuning performance, measured as modulation depth and neuronal discriminability. To simulate a recovery process compensating for the loss of inhibitory fibers, the strength of remaining inhibitory inputs was increased. By this modification, effects of inhibition loss on binaural tuning were considerably weakened, leading to an improvement of functional performance. These neuron-level observations were further confirmed by population modeling, in which binaural tuning properties of multiple LSO neurons were varied according to empirical measurements. These results demonstrate the plausibility that homeostatic plasticity could effectively counteract known age-dependent loss of inhibitory fibers in LSO and suggest that behavioral degradation of sound localization might originate from changes occurring more centrally.

show abstract

Section: Discussionmentioning

confidence: 99%

Robustness of neuronal tuning to binaural sound localization cues against age-related loss of inhibitory synaptic inputs

2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…Equivalently, models based on the correlation coefficient could account for the binaural advantage offered by such noise, without requiring a delay line, if they used the complex-valued correlation coefficient, i.e. interaural coherence [11], rather than the real-valued correlation.…”

Section: Discussionmentioning

confidence: 99%

“…For the first "cross-correlation coefficient"-based concept, however, this degree of freedom does not exist. In this case, the cross correlation, or more generally speaking the complex-valued temporal coherence of the analytical signal c [11],…”

Section: Introductionmentioning

confidence: 99%

Tone detection thresholds in interaurally delayed noise of different bandwidths

et al. 2021

Self Cite

View full text Add to dashboard Cite

Differences between the interaural phase of a noise and a target tone improve detection thresholds. The maximum masking release is obtained for detecting an antiphasic tone (Sπ) in diotic noise (N0). It has been shown in several studies that this beneﬁt gradually declines as an interaural time delay (ITD) is applied to the noise. This decline has been attributed to the reduced interaural coherence of the noise. Here, we report detection thresholds for a 500 Hz tone in masking noise with ITDs up to 8 ms and bandwidths from 25 to 1000 Hz. Reducing the noise bandwidth from 100 to 50 and 25 Hz increased the masking release for 8-ms ITD, as expected for increasing temporal coherence with decreasing bandwidth. For bandwidths of 100–1000 Hz no significant difference in masking release was observed. Detection thresholds with these wider-band noises had an ITD dependence that is fully described by the temporal coherence imposed by the typical monaurally determined auditory-filter bandwidth. A binaural model based on interaural phase-difference fluctuations accounts for the data without using delay lines.

show abstract

“…While narrow auditory filters provide a good coherence over several milliseconds, the wider analysis filters of CIs, and especially the effective channel bandwidths seen by the AN fibers, are several times broader (Frijns et al, 2001). For a bandwidth of 500 Hz, for example, not untypical for the middle region, interaural coherence vanishes within 2 ms of latency difference (Dietz & Ashida, 2021). It can be expected that larger latency differences lead to reduced ILD sensitivity and to a reduction in binaural fusion (Körtje et al, 2021).…”

Section: Causes Of Latency Mismatchmentioning

confidence: 99%

Considerations for Fitting Cochlear Implants Bimodally and to the Single-Sided Deaf

et al. 2022

Self Cite

View full text Add to dashboard Cite

When listening with a cochlear implant through one ear and acoustically through the other, binaural benefits and spatial hearing abilities are generally poorer than in other bilaterally stimulated configurations. With the working hypothesis that binaural neurons require interaurally matched inputs, we review causes for mismatch, their perceptual consequences, and experimental methods for mismatch measurements. The focus is on the three primary interaural dimensions of latency, frequency, and level. Often, the mismatch is not constant, but rather highly stimulus-dependent. We report on mismatch compensation strategies, taking into consideration the specific needs of the respective patient groups. Practical challenges typically faced by audiologists in the proposed fitting procedure are discussed. While improvement in certain areas (e.g., speaker localization) is definitely achievable, a more comprehensive mismatch compensation is a very ambitious endeavor. Even in the hypothetical ideal fitting case, performance is not expected to exceed that of a good bilateral cochlear implant user.

show abstract

Computational Models of Binaural Processing

Cited by 6 publications

References 116 publications

Robustness of neuronal tuning to binaural sound localization cues against age-related loss of inhibitory synaptic inputs

Robustness of neuronal tuning to binaural sound localization cues against age-related loss of inhibitory synaptic inputs

Tone detection thresholds in interaurally delayed noise of different bandwidths

Considerations for Fitting Cochlear Implants Bimodally and to the Single-Sided Deaf

Contact Info

Product

Resources

About