Asymmetric temporal envelope encoding: Implications for within- and across-ear envelope comparison

Anderson, Sean R.; Kan, Alan; Litovsky, Ruth Y.

doi:10.1121/1.5121423

Cited by 7 publications

(12 citation statements)

References 82 publications

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“…We further hypothesized that this would occur if the dynamic range was decreased in only one ear, listeners would also experience increased fusion and decreased speech understanding. This would be consistent with previous literature concerning discrimination of binaural cues in listeners with NH and BiCIs ( Ihlefeld et al, 2015 ; Anderson et al, 2019b , 2022 ). Alternatively, differences between the ears themselves may cause problems for listeners with BiCIs (e.g., Yoon et al, 2011 ).…”

Section: Introductionsupporting

confidence: 93%

“…Studies of patients with BiCIs and simulations in NH suggest that interaurally asymmetric hearing outcomes may limit performance in binaural tasks ( Mosnier et al, 2009 ; Yoon et al, 2011 ; Ihlefeld et al, 2015 ; Goupell et al, 2016 , 2018 ; Anderson et al, 2019b , 2022 ; Bakal et al, 2021 ). These studies assessed sensitivity to binaural cues, sound source localization, and speech understanding in background noise, and related them to asymmetry in sensitivity to temporal cues or monaural speech understanding.…”

Section: Introductionmentioning

confidence: 99%

“…To address interaurally asymmetric hearing more directly, some studies first indexed or manipulated temporal fidelity in both ears, then assessed sensitivity to binaural cues. The ear with poorer temporal fidelity predicted the amount of sensitivity to binaural cues ( Ihlefeld et al, 2015 ; Anderson et al, 2019b , 2022 ). Simulations in NH used asymmetric dynamic range (i.e., amplitude modulation depth), where smaller dynamic ranges in listeners with BiCIs have resulted in poorer sensitivity to binaural cues ( Ihlefeld et al, 2014 ; Todd et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

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Interaural asymmetry of dynamic range: Abnormal fusion, bilateral interference, and shifts in attention

Anderson

Gallun²,

Litovsky³

2023

Front. Neurosci.

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Speech information in the better ear interferes with the poorer ear in patients with bilateral cochlear implants (BiCIs) who have large asymmetries in speech intelligibility between ears. The goal of the present study was to assess how each ear impacts, and whether one dominates, speech perception using simulated CI processing in older and younger normal-hearing (ONH and YNH) listeners. Dynamic range (DR) was manipulated symmetrically or asymmetrically across spectral bands in a vocoder. We hypothesized that if abnormal integration of speech information occurs with asymmetrical speech understanding, listeners would demonstrate an atypical preference in accuracy when reporting speech presented to the better ear and fusion of speech between the ears (i.e., an increased number of one-word responses when two words were presented). Results from three speech conditions showed that: (1) When the same word was presented to both ears, speech identification accuracy decreased if one or both ears decreased in DR, but listeners usually reported hearing one word. (2) When two words with different vowels were presented to both ears, speech identification accuracy and percentage of two-word responses decreased consistently as DR decreased in one or both ears. (3) When two rhyming words (e.g., bed and led) previously shown to phonologically fuse between ears (e.g., bled) were presented, listeners instead demonstrated interference as DR decreased. The word responded in (2) and (3) came from the right (symmetric) or better (asymmetric) ear, especially in (3) and for ONH listeners in (2). These results suggest that the ear with poorer dynamic range is downweighted by the auditory system, resulting in abnormal fusion and interference, especially for older listeners.

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Section: Introductionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interaural asymmetry of dynamic range: Abnormal fusion, bilateral interference, and shifts in attention

Anderson

Gallun²,

Litovsky³

2023

Front. Neurosci.

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“…Ihlefeld et al [ 99 ] showed that the ear with poorer temporal sensitivity could predict the amount of ITD sensitivity in adults with BiCIs. A related study in listeners with NH showed that, for comparisons of temporal information of simultaneously presented sounds within- or across-ears, poorer fidelity of temporal information in only one of the two places-of-stimulation degrades performance [ 100 ]. Together with the results of Reeder et al [ 14 ], these studies suggest that the more important variable is not the delay between ears, but the longer length of deafness, likely leading to greater deterioration of the auditory periphery due to a lack of stimulation.…”

Section: Discussionmentioning

confidence: 99%

Sound source localization patterns and bilateral cochlear implants: Age at onset of deafness effects

et al. 2022

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The ability to determine a sound’s location is critical in everyday life. However, sound source localization is severely compromised for patients with hearing loss who receive bilateral cochlear implants (BiCIs). Several patient factors relate to poorer performance in listeners with BiCIs, associated with auditory deprivation, experience, and age. Critically, characteristic errors are made by patients with BiCIs (e.g., medial responses at lateral target locations), and the relationship between patient factors and the type of errors made by patients has seldom been investigated across individuals. In the present study, several different types of analysis were used to understand localization errors and their relationship with patient-dependent factors (selected based on their robustness of prediction). Binaural hearing experience is required for developing accurate localization skills, auditory deprivation is associated with degradation of the auditory periphery, and aging leads to poorer temporal resolution. Therefore, it was hypothesized that earlier onsets of deafness would be associated with poorer localization acuity and longer periods without BiCI stimulation or older age would lead to greater amounts of variability in localization responses. A novel machine learning approach was introduced to characterize the types of errors made by listeners with BiCIs, making them simple to interpret and generalizable to everyday experience. Sound localization performance was measured in 48 listeners with BiCIs using pink noise trains presented in free-field. Our results suggest that older age at testing and earlier onset of deafness are associated with greater average error, particularly for sound sources near the center of the head, consistent with previous research. The machine learning analysis revealed that variability of localization responses tended to be greater for individuals with earlier compared to later onsets of deafness. These results suggest that early bilateral hearing is essential for best sound source localization outcomes in listeners with BiCIs.

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“…While this task worked well for listeners with HI, listeners with NH made pitch confusions across the two ears for closely spaced frequencies so that it was not possible to provide useful feedback. One additional alternative was provided by Anderson et al (2019) in a related experimental paradigm where listeners judged whether the same or different amplitude modulation rates were presented to different ears using sinusoidally amplitude-modulated tones. They used a 1I-2AFC task like the one in the present study, except that they provided visual feedback on whether amplitude modulation rates were in fact the same or different.…”

Section: Limitationsmentioning

confidence: 99%

Binaural pitch fusion: Effects of sound level in listeners with normal hearing

Anderson

Glickman

et al. 2020

Hearing Research

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Pitch is an essential cue that allows the auditory system to distinguish between sound sources. Pitch cues are less useful when listeners are not able to discriminate different pitches between the two ears, a problem encountered by listeners with hearing impairment (HI). Many listeners with HI will fuse the pitch of two dichotically presented tones over a larger range of interaural frequency disparities, i.e., have a broader fusion range, than listeners with normal hearing (NH). One potential explanation for broader fusion in listeners with HI is that hearing aids stimulate at high sound levels. The present study investigated effects of overall sound levels on pitch fusion in listeners with NH. It was hypothesized that if sound level increased, then fusion range would increase. Fusion ranges were measured by presenting a fixed frequency tone to a reference ear simultaneously with a variable frequency tone to the opposite ear and finding the range of frequencies that were fused with the reference frequency. No significant effects of sound level (comfortable level ± 15 decibels) on fusion range were found, even when tested within the range of levels where some listeners with HI show large fusion ranges. Results suggest that increased sound level does not explain increased fusion range in listeners with HI and imply that other factors associated with hearing loss might play a larger role.

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Asymmetric temporal envelope encoding: Implications for within- and across-ear envelope comparison

Cited by 7 publications

References 82 publications

Interaural asymmetry of dynamic range: Abnormal fusion, bilateral interference, and shifts in attention

Interaural asymmetry of dynamic range: Abnormal fusion, bilateral interference, and shifts in attention

Sound source localization patterns and bilateral cochlear implants: Age at onset of deafness effects

Binaural pitch fusion: Effects of sound level in listeners with normal hearing

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