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Best V, Conroy C. Relating monaural and binaural measures of modulation sensitivity in listeners with and without hearing loss. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2024; 156:1543-1551. [PMID: 39235271 PMCID: PMC11379497 DOI: 10.1121/10.0028517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 08/15/2024] [Indexed: 09/06/2024]
Abstract
Listeners are sensitive to interaural time differences carried in the envelope of high-frequency sounds (ITDENV), but the salience of this cue depends on certain properties of the envelope and, in particular, on the presence/depth of amplitude modulation (AM) in the envelope. This study tested the hypothesis that individuals with sensorineural hearing loss, who show enhanced sensitivity to AM under certain conditions, would also show superior ITDENV sensitivity under those conditions. The second hypothesis was that variations in ITDENV sensitivity across individuals can be related to variations in sensitivity to AM. To enable a direct comparison, a standard adaptive AM detection task was used along with a modified version of it designed to measure ITDENV sensitivity. The stimulus was a 4-kHz tone modulated at rates of 32, 64, or 128 Hz and presented at a 30 dB sensation level. Both tasks were attempted by 16 listeners with normal hearing and 16 listeners with hearing loss. Consistent with the hypotheses, AM and ITDENV thresholds were correlated and tended to be better in listeners with hearing loss. A control experiment emphasized that absolute level may be a consideration when interpreting the group effects.
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Affiliation(s)
- Virginia Best
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, Massachusetts 02215, USA
| | - Christopher Conroy
- Department of Speech, Language and Hearing Sciences, Boston University, Boston, Massachusetts 02215, USA
- Department of Biological and Vision Sciences, State University of New York, College of Optometry, New York, New York 10036, USA
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Hu H, Klug J, Dietz M. Simulation of ITD-Dependent Single-Neuron Responses Under Electrical Stimulation and with Amplitude-Modulated Acoustic Stimuli. J Assoc Res Otolaryngol 2022; 23:535-550. [PMID: 35334001 PMCID: PMC9437183 DOI: 10.1007/s10162-021-00823-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Accepted: 11/03/2021] [Indexed: 11/30/2022] Open
Abstract
Interaural time difference (ITD) sensitivity with cochlear implant stimulation is remarkably similar to envelope ITD sensitivity using conventional acoustic stimulation. This holds true for human perception, as well as for neural response rates recorded in the inferior colliculus of several mammalian species. We hypothesize that robust excitatory-inhibitory (EI) interaction is the dominant mechanism. Therefore, we connected the same single EI-model neuron to either a model of the normal acoustic auditory periphery or to a model of the electrically stimulated auditory nerve. The model captured most features of the experimentally obtained response properties with electric stimulation, such as the shape of rate-ITD functions, the dependence on stimulation level, and the pulse rate or modulation-frequency dependence. Rate-ITD functions with high-rate, amplitude-modulated electric stimuli were very similar to their acoustic counterparts. Responses obtained with unmodulated electric pulse trains most resembled acoustic filtered clicks. The fairly rapid decline of ITD sensitivity at rates above 300 pulses or cycles per second is correctly simulated by the 3.1-ms time constant of the inhibitory post-synaptic conductance. As the model accounts for these basic properties, it is expected to help in understanding and quantifying the binaural hearing abilities with electric stimulation when integrated in bigger simulation frameworks.
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Affiliation(s)
- Hongmei Hu
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany.
| | - Jonas Klug
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany
| | - Mathias Dietz
- Department of Medical Physics and Acoustics and Cluster of Excellence "Hearing4all", University of Oldenburg, 26129, Oldenburg, Germany
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Encke J, Dietz M. Influence of envelope fluctuation on the lateralization of interaurally delayed low-frequency stimuli. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:3101. [PMID: 34717449 DOI: 10.1121/10.0006571] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
Disregarding onset and offset effects, interaurally delaying a 500 Hz tone by 1.5 ms is identical to advancing it by 0.5 ms. When presented over headphones, humans indeed perceive such a tone lateralized toward the side of the nominal lag. Any stimulus other than a tone has more than one frequency component and is thus unambiguous. It has been shown that phase ambiguity can be resolved when increasing the stimulus bandwidth. This has mostly been attributed to the integration of information across frequencies. Additionally, interaural timing information conveyed in the stimulus envelope within a single frequency channel is a second possible cue that could help to resolve phase ambiguity. This study employs stimuli designed to differ in the amount of envelope fluctuation while retaining the same power spectral density as well as interaural differences. Any difference in lateralization must thus be a result of the difference in envelope. The results show that stimuli with strong envelope fluctuation require significantly smaller bandwidths to resolve phase ambiguity when compared to stimuli with weak envelope fluctuation. This suggests that within-channel information is an important cue used to resolve phase ambiguity.
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Affiliation(s)
- Jörg Encke
- Department für Medizinische Physik und Akustik, Universität Oldenburg, 26111 Oldenburg, Germany
| | - Mathias Dietz
- Department für Medizinische Physik und Akustik, Universität Oldenburg, 26111 Oldenburg, Germany
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Sensitivity to interaural time differences in the inferior colliculus of cochlear implanted rats with or without hearing experience. Hear Res 2021; 408:108305. [PMID: 34315027 DOI: 10.1016/j.heares.2021.108305] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 06/24/2021] [Accepted: 06/29/2021] [Indexed: 01/11/2023]
Abstract
For deaf patients cochlear implants (CIs) can restore substantial amounts of functional hearing. However, binaural hearing, and in particular, the perception of interaural time differences (ITDs) with current CIs has been found to be notoriously poor, especially in the event of early hearing loss. One popular hypothesis for these deficits posits that a lack of early binaural experience may be a principal cause of poor ITD perception in pre-lingually deaf CI patients. This is supported by previous electrophysiological studies done in neonatally deafened, bilateral CI-stimulated animals showing reduced ITD sensitivity. However, we have recently demonstrated that neonatally deafened CI rats can quickly learn to discriminate microsecond ITDs under optimized stimulation conditions which suggests that the inability of human CI users to make use of ITDs is not due to lack of binaural hearing experience during development. In the study presented here, we characterized ITD sensitivity and tuning of inferior colliculus neurons under bilateral CI stimulation of neonatally deafened and hearing experienced rats. The hearing experienced rats were not deafened prior to implantation. Both cohorts were implanted bilaterally between postnatal days 64-77 and recorded immediately following surgery. Both groups showed comparably large proportions of ITD sensitive multi-units in the inferior colliculus (Deaf: 84.8%, Hearing: 82.5%), and the strength of ITD tuning, quantified as mutual information between response and stimulus ITD, was independent of hearing experience. However, the shapes of tuning curves differed substantially between both groups. We observed four main clusters of tuning curves - trough, contralateral, central, and ipsilateral tuning. Interestingly, over 90% of multi-units for hearing experienced rats showed predominantly contralateral tuning, whereas as many as 50% of multi-units in neonatally deafened rats were centrally tuned. However, when we computed neural d' scores to predict likely limits on performance in sound lateralization tasks, we did not find that these differences in tuning shapes predicted worse psychoacoustic performance for the neonatally deafened animals. We conclude that, at least in rats, substantial amounts of highly precise, "innate" ITD sensitivity can be found even after profound hearing loss throughout infancy. However, ITD tuning curve shapes appear to be strongly influenced by auditory experience although substantial lateralization encoding is present even in its absence.
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Haywood NR, Undurraga JA, McAlpine D. The influence of envelope shape on the lateralization of amplitude-modulated, low-frequency sound. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 149:3133. [PMID: 34241105 DOI: 10.1121/10.0004788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 04/06/2021] [Indexed: 06/13/2023]
Abstract
For abruptly gated sound, interaural time difference (ITD) cues at onset carry greater perceptual weight than those following. This research explored how envelope shape influences such carrier ITD weighting. Experiment 1 assessed the perceived lateralization of a tonal binaural beat that transitioned through ITD (diotic envelope, mean carrier frequency of 500 Hz). Listeners' left/right lateralization judgments were compared to those for static-ITD tones. For an 8 Hz sinusoidally amplitude-modulated envelope, ITD cues 24 ms after onset well-predicted reported sidedness. For an equivalent-duration "abrupt" envelope, which was unmodulated besides 20-ms onset/offset ramps, reported sidedness corresponded to ITDs near onset (e.g., 6 ms). However, unlike for sinusoidal amplitude modulation, ITDs toward offset seemingly also influenced perceived sidedness. Experiment 2 adjusted the duration of the offset ramp (25-75 ms) and found evidence for such offset weighting only for the most abrupt ramp tested. In experiment 3, an ITD was imposed on a brief segment of otherwise diotic filtered noise. Listeners discriminated right- from left-leading ITDs. In sinusoidal amplitude modulation, thresholds were lowest when the ITD segment occurred during rising amplitude. For the abrupt envelope, the lowest thresholds were observed when the segment occurred at either onset or offset. These experiments demonstrate the influence of envelope profile on carrier ITD sensitivity.
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Affiliation(s)
- Nicholas R Haywood
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Jaime A Undurraga
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
| | - David McAlpine
- Department of Linguistics, Faculty of Medicine, Health and Human Sciences, Macquarie Hearing, Macquarie University, Sydney, New South Wales 2109, Australia
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Enhancing the sensitivity of the envelope-following response for cochlear synaptopathy screening in humans: The role of stimulus envelope. Hear Res 2020; 400:108132. [PMID: 33333426 DOI: 10.1016/j.heares.2020.108132] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Revised: 10/25/2020] [Accepted: 11/25/2020] [Indexed: 02/07/2023]
Abstract
Auditory de-afferentation, a permanent reduction in the number of inner-hair-cells and auditory-nerve synapses due to cochlear damage or synaptopathy, can reliably be quantified using temporal bone histology and immunostaining. However, there is an urgent need for non-invasive markers of synaptopathy to study its perceptual consequences in live humans and to develop effective therapeutic interventions. While animal studies have identified candidate auditory-evoked-potential (AEP) markers for synaptopathy, their interpretation in humans has suffered from translational issues related to neural generator differences, unknown hearing-damage histopathologies or lack of measurement sensitivity. To render AEP-based markers of synaptopathy more sensitive and differential to the synaptopathy aspect of sensorineural hearing loss, we followed a combined computational and experimental approach. Starting from the known characteristics of auditory-nerve physiology, we optimized the stimulus envelope to stimulate the available auditory-nerve population optimally and synchronously to generate strong envelope-following-responses (EFRs). We further used model simulations to explore which stimuli evoked a response that was sensitive to synaptopathy, while being maximally insensitive to possible co-existing outer-hair-cell pathologies. We compared the model-predicted trends to AEPs recorded in younger and older listeners (N=44, 24f) who had normal or impaired audiograms with suspected age-related synaptopathy in the older cohort. We conclude that optimal stimulation paradigms for EFR-based quantification of synaptopathy should have sharply rising envelope shapes, a minimal plateau duration of 1.7-2.1 ms for a 120-Hz modulation rate, and inter-peak intervals which contain near-zero amplitudes. From our recordings, the optimal EFR-evoking stimulus had a rectangular envelope shape with a 25% duty cycle and a 95% modulation depth. Older listeners with normal or impaired audiometric thresholds showed significantly reduced EFRs, which were consistent with how (age-induced) synaptopathy affected these responses in the model.
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Klug J, Schmors L, Ashida G, Dietz M. Neural rate difference model can account for lateralization of high-frequency stimuli. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2020; 148:678. [PMID: 32873019 DOI: 10.1121/10.0001602] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
Lateralization of complex high-frequency sounds is conveyed by interaural level differences (ILDs) and interaural time differences (ITDs) in the envelope. In this work, the authors constructed an auditory model and simulate data from three previous behavioral studies obtained with, in total, over 1000 different amplitude-modulated stimuli. The authors combine a well-established auditory periphery model with a functional count-comparison model for binaural excitatory-inhibitory (EI) interaction. After parameter optimization of the EI-model stage, the hemispheric rate-difference between pairs of EI-model neurons relates linearly with the extent of laterality in human listeners. If a certain ILD and a certain envelope ITD each cause a similar extent of laterality, they also produce a similar rate difference in the same model neurons. After parameter optimization, the model accounts for 95.7% of the variance in the largest dataset, in which amplitude modulation depth, rate of modulation, modulation exponent, ILD, and envelope ITD were varied. The model also accounts for 83% of the variances in each of the other two datasets using the same EI model parameters.
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Affiliation(s)
- Jonas Klug
- Department of Medical Physics and Acoustics, University of Oldenburg, 26129 Oldenburg, Germany
| | - Lisa Schmors
- Department of Medical Physics and Acoustics, University of Oldenburg, 26129 Oldenburg, Germany
| | - Go Ashida
- Department of Neuroscience, University of Oldenburg, 26129 Oldenburg, Germany
| | - Mathias Dietz
- Department of Medical Physics and Acoustics, University of Oldenburg, 26129 Oldenburg, Germany
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Van Canneyt J, Hofmann M, Wouters J, Francart T. The effect of stimulus envelope shape on the auditory steady-state response. Hear Res 2019; 380:22-34. [DOI: 10.1016/j.heares.2019.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 04/23/2019] [Accepted: 05/23/2019] [Indexed: 01/01/2023]
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Brown AD, Anbuhl KL, Gilmer JI, Tollin DJ. Between-ear sound frequency disparity modulates a brain stem biomarker of binaural hearing. J Neurophysiol 2019; 122:1110-1122. [PMID: 31314646 PMCID: PMC6766741 DOI: 10.1152/jn.00057.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 11/22/2022] Open
Abstract
The auditory brain stem response (ABR) is an evoked potential that indexes a cascade of neural events elicited by sound. In the present study we evaluated the influence of sound frequency on a derived component of the ABR known as the binaural interaction component (BIC). Specifically, we evaluated the effect of acoustic interaural (between-ear) frequency mismatch on BIC amplitude. Goals were to 1) increase basic understanding of sound features that influence this long-studied auditory potential and 2) gain insight about the persistence of the BIC with interaural electrode mismatch in human users of bilateral cochlear implants, presently a limitation on the prospective utility of the BIC in audiological settings. Data were collected in an animal model that is audiometrically similar to humans, the chinchilla (Chinchilla lanigera; 6 females). Frequency disparities and amplitudes of acoustic stimuli were varied over broad ranges, and associated variation of BIC amplitude was quantified. Subsequently, responses were simulated with the use of established models of the brain stem pathway thought to underlie the BIC. Collectively, the data demonstrate that at high sound intensities (≥85 dB SPL), the acoustically elicited BIC persisted with interaurally disparate stimulation (click frequencies ≥1.5 octaves apart). However, sharper tuning emerged at moderate sound intensities (65 dB SPL), with the largest BIC occurring for stimulus frequencies within ~0.8 octaves, equivalent to ±1 mm in cochlear place. Such responses were consistent with simulated responses of the presumed brain stem generator of the BIC, the lateral superior olive. The data suggest that leveraging focused electrical stimulation strategies could improve BIC-based bilateral cochlear implant fitting outcomes.NEW & NOTEWORTHY Traditional hearing tests evaluate each ear independently. Diagnosis and treatment of binaural hearing dysfunction remains a basic challenge for hearing clinicians. We demonstrate in an animal model that the prospective utility of a noninvasive electrophysiological signature of binaural function, the binaural interaction component (BIC), depends strongly on the intensity of auditory stimulation. Data suggest that more informative BIC measurements could be obtained with clinical protocols leveraging stimuli restricted in effective bandwidth.
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Affiliation(s)
- Andrew D Brown
- Department of Speech and Hearing Sciences, University of Washington, Seattle, Washington
| | - Kelsey L Anbuhl
- Center for Neural Science, New York University, New York, New York
| | - Jesse I Gilmer
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
- Neuroscience Training Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Daniel J Tollin
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
- Neuroscience Training Program, University of Colorado School of Medicine, Aurora, Colorado
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, Colorado
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Dietz M, Lestang JH, Majdak P, Stern RM, Marquardt T, Ewert SD, Hartmann WM, Goodman DFM. A framework for testing and comparing binaural models. Hear Res 2017; 360:92-106. [PMID: 29208336 DOI: 10.1016/j.heares.2017.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/03/2017] [Accepted: 11/24/2017] [Indexed: 11/19/2022]
Abstract
Auditory research has a rich history of combining experimental evidence with computational simulations of auditory processing in order to deepen our theoretical understanding of how sound is processed in the ears and in the brain. Despite significant progress in the amount of detail and breadth covered by auditory models, for many components of the auditory pathway there are still different model approaches that are often not equivalent but rather in conflict with each other. Similarly, some experimental studies yield conflicting results which has led to controversies. This can be best resolved by a systematic comparison of multiple experimental data sets and model approaches. Binaural processing is a prominent example of how the development of quantitative theories can advance our understanding of the phenomena, but there remain several unresolved questions for which competing model approaches exist. This article discusses a number of current unresolved or disputed issues in binaural modelling, as well as some of the significant challenges in comparing binaural models with each other and with the experimental data. We introduce an auditory model framework, which we believe can become a useful infrastructure for resolving some of the current controversies. It operates models over the same paradigms that are used experimentally. The core of the proposed framework is an interface that connects three components irrespective of their underlying programming language: The experiment software, an auditory pathway model, and task-dependent decision stages called artificial observers that provide the same output format as the test subject.
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Affiliation(s)
- Mathias Dietz
- National Centre for Audiology, Western University, London, ON, Canada.
| | - Jean-Hugues Lestang
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
| | - Piotr Majdak
- Institut für Schallforschung, Österreichische Akademie der Wissenschaften, Wien, Austria
| | | | | | - Stephan D Ewert
- Medizinische Physik, Universität Oldenburg, Oldenburg, Germany
| | | | - Dan F M Goodman
- Department of Electrical and Electronic Engineering, Imperial College London, London, United Kingdom
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