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Cleary M, DeRoy Milvae K, Nguyen N, Bernstein JGW, Goupell MJ. Effect of experimentally introduced interaural frequency mismatch on sentence recognition in bilateral cochlear-implant listeners. JASA EXPRESS LETTERS 2023; 3:044401. [PMID: 37096891 PMCID: PMC10080388 DOI: 10.1121/10.0017705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
Bilateral cochlear-implant users experience interaural frequency mismatch because of asymmetries in array insertion and frequency-to-electrode assignment. To explore the acute perceptual consequences of such mismatch, sentence recognition in quiet was measured in nine bilateral cochlear-implant listeners as frequency allocations in the poorer ear were shifted by ±1.5, ±3, and ±4.5 mm using experimental programs. Shifts in frequency allocation >3 mm reduced bilateral sentence scores below those for the better ear alone, suggesting that the poorer ear interfered with better-ear perception. This was not a result of fewer active channels; deactivating electrodes without frequency shifting had minimal effect.
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Affiliation(s)
- Miranda Cleary
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Kristina DeRoy Milvae
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Nicole Nguyen
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
| | - Joshua G W Bernstein
- National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, Maryland 20889, , , , ,
| | - Matthew J Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, Maryland 20742, USA
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Cleary M, DeRoy Milvae K, Nguyen N, Bernstein JGW, Goupell MJ. Effect of experimentally introduced interaural frequency mismatch on sentence recognition in bilateral cochlear-implant listeners. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.01.06.23284274. [PMID: 36711489 PMCID: PMC9882401 DOI: 10.1101/2023.01.06.23284274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Bilateral cochlear-implant users experience interaural frequency mismatch because of asymmetries in array insertion and frequency-to-electrode assignment. To explore the acute perceptual consequences of such mismatch, sentence recognition in quiet was measured in nine bilateral cochlear-implant listeners as frequency allocations in the poorer ear were shifted by ±1.5, ±3 and ±4.5 mm using experimental programs. Shifts in frequency allocation >3 mm were found to reduce bilateral sentence scores below those for the better ear alone, suggesting that the poorer ear interfered with better-ear perception. This was not a result of fewer active channels; deactivating electrodes without frequency shifting had minimal effect.
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Affiliation(s)
- Miranda Cleary
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA
| | - Kristina DeRoy Milvae
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA,Department of Communicative Disorders and Sciences, University at Buffalo, Buffalo, NY, USA
| | - Nicole Nguyen
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA
| | - Joshua G. W. Bernstein
- National Military Audiology and Speech Pathology Center, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Matthew J. Goupell
- Department of Hearing and Speech Sciences, University of Maryland, College Park, MD, USA
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Angular Electrode Insertion Depth and Speech Perception in Adults With a Cochlear Implant: A Systematic Review. Otol Neurotol 2020; 40:900-910. [PMID: 31135680 PMCID: PMC6641467 DOI: 10.1097/mao.0000000000002298] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Objective: By discussing the design, findings, strengths, and weaknesses of available studies investigating the influence of angular insertion depth on speech perception, we intend to summarize the current status of evidence; and using evidence based conclusions, possibly contribute to the determination of the optimal cochlear implant (CI) electrode position. Data Sources: Our search strategy yielded 10,877 papers. PubMed, Ovid EMBASE, Web of Science, and the Cochrane Library were searched up to June 1, 2018. Both keywords and free-text terms, related to patient population, predictive factor, and outcome measurements were used. There were no restrictions in languages or year of publication. Study Selection: Seven articles were included in this systematic review. Articles eligible for inclusion: (a) investigated cochlear implantation of any CI system in adults with post-lingual onset of deafness and normal cochlear anatomy; (b) investigated the relationship between angular insertion depth and speech perception; (c) measured angular insertion depth on imaging; and (d) measured speech perception at, or beyond 1-year post-activation. Data Extraction and Synthesis: In included studies; quality was judged low-to-moderate and risk of bias, evaluated using a Quality-in-Prognostic-Studies-tool (QUIPS), was high. Included studies were too heterogeneous to perform meta-analyses, therefore, effect estimates of the individual studies are presented. Six out of seven included studies found no effect of angular insertion depth on speech perception. Conclusion: All included studies are characterized by methodological flaws, and therefore, evidence-based conclusions regarding the influence of angular insertion depth cannot be drawn to date.
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Karoui C, James C, Barone P, Bakhos D, Marx M, Macherey O. Searching for the Sound of a Cochlear Implant: Evaluation of Different Vocoder Parameters by Cochlear Implant Users With Single-Sided Deafness. Trends Hear 2020; 23:2331216519866029. [PMID: 31533581 PMCID: PMC6753516 DOI: 10.1177/2331216519866029] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Cochlear implantation in subjects with single-sided deafness (SSD) offers a unique opportunity to directly compare the percepts evoked by a cochlear implant (CI) with those evoked acoustically. Here, nine SSD-CI users performed a forced-choice task evaluating the similarity of speech processed by their CI with speech processed by several vocoders presented to their healthy ear. In each trial, subjects heard two intervals: their CI followed by a certain vocoder in Interval 1 and their CI followed by a different vocoder in Interval 2. The vocoders differed either (i) in carrier type-(sinusoidal [SINE], bandfiltered noise [NOISE], and pulse-spreading harmonic complex) or (ii) in frequency mismatch between the analysis and synthesis frequency ranges-(no mismatch, and two frequency-mismatched conditions of 2 and 4 equivalent rectangular bandwidths [ERBs]). Subjects had to state in which of the two intervals the CI and vocoder sounds were more similar. Despite a large intersubject variability, the PSHC vocoder was judged significantly more similar to the CI than SINE or NOISE vocoders. Furthermore, the No-mismatch and 2-ERB mismatch vocoders were judged significantly more similar to the CI than the 4-ERB mismatch vocoder. The mismatch data were also interpreted by comparing spiral ganglion characteristic frequencies with electrode contact positions determined from postoperative computed tomography scans. Only one subject demonstrated a pattern of preference consistent with adaptation to the CI sound processor frequency-to-electrode allocation table and two subjects showed possible partial adaptation. Those subjects with adaptation patterns presented overall small and consistent frequency mismatches across their electrode arrays.
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Affiliation(s)
- Chadlia Karoui
- Centre de Recherche Cerveau et Cognition, Toulouse, France.,Cochlear France SAS, Toulouse, France
| | - Chris James
- Cochlear France SAS, Toulouse, France.,Department of Otology-Neurotology and Skull Base Surgery, Purpan University Hospital, Toulouse, France
| | - Pascal Barone
- Centre de Recherche Cerveau et Cognition, Toulouse, France
| | - David Bakhos
- Université François-Rabelais de Tours, CHRU de Tours, France.,Ear Nose and Throat department, CHUR de Tours, Tours, France
| | - Mathieu Marx
- Centre de Recherche Cerveau et Cognition, Toulouse, France.,Department of Otology-Neurotology and Skull Base Surgery, Purpan University Hospital, Toulouse, France
| | - Olivier Macherey
- Aix Marseille University, CNRS, Centrale Marseille, LMA, Marseille, France
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The Effect of Simulated Interaural Frequency Mismatch on Speech Understanding and Spatial Release From Masking. Ear Hear 2019; 39:895-905. [PMID: 29337763 DOI: 10.1097/aud.0000000000000541] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The binaural-hearing system interaurally compares inputs, which underlies the ability to localize sound sources and to better understand speech in complex acoustic environments. Cochlear implants (CIs) are provided in both ears to increase binaural-hearing benefits; however, bilateral CI users continue to struggle with understanding speech in the presence of interfering sounds and do not achieve the same level of spatial release from masking (SRM) as normal-hearing listeners. One reason for diminished SRM in CI users could be that the electrode arrays are inserted at different depths in each ear, which would cause an interaural frequency mismatch. Because interaural frequency mismatch diminishes the salience of interaural differences for relatively simple stimuli, it may also diminish binaural benefits for spectral-temporally complex stimuli like speech. This study evaluated the effect of simulated frequency-to-place mismatch on speech understanding and SRM. DESIGN Eleven normal-hearing listeners were tested on a speech understanding task. There was a female target talker who spoke five-word sentences from a closed set of words. There were two interfering male talkers who spoke unrelated sentences. Nonindividualized head-related transfer functions were used to simulate a virtual auditory space. The target was presented from the front (0°), and the interfering speech was either presented from the front (colocated) or from 90° to the right (spatially separated). Stimuli were then processed by an eight-channel vocoder with tonal carriers to simulate aspects of listening through a CI. Frequency-to-place mismatch ("shift") was introduced by increasing the center frequency of the synthesis filters compared with the corresponding analysis filters. Speech understanding was measured for different shifts (0, 3, 4.5, and 6 mm) and target-to-masker ratios (TMRs: +10 to -10 dB). SRM was calculated as the difference in the percentage of correct words for the colocated and separated conditions. Two types of shifts were tested: (1) bilateral shifts that had the same frequency-to-place mismatch in both ears, but no interaural frequency mismatch, and (2) unilateral shifts that produced an interaural frequency mismatch. RESULTS For the bilateral shift conditions, speech understanding decreased with increasing shift and with decreasing TMR, for both colocated and separate conditions. There was, however, no interaction between shift and spatial configuration; in other words, SRM was not affected by shift. For the unilateral shift conditions, speech understanding decreased with increasing interaural mismatch and with decreasing TMR for both the colocated and spatially separated conditions. Critically, there was a significant interaction between the amount of shift and spatial configuration; in other words, SRM decreased for increasing interaural mismatch. CONCLUSIONS A frequency-to-place mismatch in one or both ears resulted in decreased speech understanding. SRM, however, was only affected in conditions with unilateral shifts and interaural frequency mismatch. Therefore, matching frequency information between the ears provides listeners with larger binaural-hearing benefits, for example, improved speech understanding in the presence of interfering talkers. A clinical procedure to reduce interaural frequency mismatch when programming bilateral CIs may improve benefits in speech segregation that are due to binaural-hearing abilities.
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Fitzgerald MB, Prosolovich K, Tan CT, Glassman EK, Svirsky MA. Self-Selection of Frequency Tables with Bilateral Mismatches in an Acoustic Simulation of a Cochlear Implant. J Am Acad Audiol 2017; 28:385-394. [PMID: 28534729 PMCID: PMC5563263 DOI: 10.3766/jaaa.15077] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Many recipients of bilateral cochlear implants (CIs) may have differences in electrode insertion depth. Previous reports indicate that when a bilateral mismatch is imposed, performance on tests of speech understanding or sound localization becomes worse. If recipients of bilateral CIs cannot adjust to a difference in insertion depth, adjustments to the frequency table may be necessary to maximize bilateral performance. PURPOSE The purpose of this study was to examine the feasibility of using real-time manipulations of the frequency table to offset any decrements in performance resulting from a bilateral mismatch. RESEARCH DESIGN A simulation of a CI was used because it allows for explicit control of the size of a bilateral mismatch. Such control is not available with users of CIs. STUDY SAMPLE A total of 31 normal-hearing young adults participated in this study. DATA COLLECTION AND ANALYSIS Using a CI simulation, four bilateral mismatch conditions (0, 0.75, 1.5, and 3 mm) were created. In the left ear, the analysis filters and noise bands of the CI simulation were the same. In the right ear, the noise bands were shifted higher in frequency to simulate a bilateral mismatch. Then, listeners selected a frequency table in the right ear that was perceived as maximizing bilateral speech intelligibility. Word-recognition scores were then assessed for each bilateral mismatch condition. Listeners were tested with both a standard frequency table, which preserved a bilateral mismatch, or with their self-selected frequency table. RESULTS Consistent with previous reports, bilateral mismatches of 1.5 and 3 mm yielded decrements in word recognition when the standard table was used in both ears. However, when listeners used the self-selected frequency table, performance was the same regardless of the size of the bilateral mismatch. CONCLUSIONS Self-selection of a frequency table appears to be a feasible method for ameliorating the negative effects of a bilateral mismatch. These data may have implications for recipients of bilateral CIs who cannot adapt to a bilateral mismatch, because they suggest that (1) such individuals may benefit from modification of the frequency table in one ear and (2) self-selection of a "most intelligible" frequency table may be a useful tool for determining how the frequency table should be altered to optimize speech recognition.
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Affiliation(s)
- Matthew B. Fitzgerald
- Department of Otolaryngology – Head and Neck Surgery, Stanford Ear Institute, Stanford University, Palo Alto, CA
- Department of Otolaryngology, New York University School of Medicine, New York, NY
| | - Ksenia Prosolovich
- Department of Otolaryngology, University of Southern California, Los Angeles, CA
| | - Chin-Tuan Tan
- Department of Otolaryngology, New York University School of Medicine, New York, NY
| | | | - Mario A. Svirsky
- Department of Otolaryngology, New York University School of Medicine, New York, NY
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Malherbe TK, Hanekom T, Hanekom JJ. Constructing a three-dimensional electrical model of a living cochlear implant user's cochlea. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2016; 32:e02751. [PMID: 26430919 DOI: 10.1002/cnm.2751] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 09/18/2015] [Accepted: 09/30/2015] [Indexed: 06/05/2023]
Abstract
BACKGROUND Hearing performance varies greatly among users of cochlear implants. Current three-dimensional cochlear models that predict the electrical fields inside a stimulated cochlea and their effect on neural excitation are generally based on a generic human or guinea pig cochlear shape that does not take inter-user morphological variations into account. This precludes prediction of user-specific performance. AIMS The aim of this study is to develop a model of the implanted cochlea of a specific living human individual and to assess if the inclusion of morphological variations in cochlear models affects predicted outcomes significantly. METHODS Five three-dimensional electric volume conduction models of the implanted cochleae of individual living users were constructed from standard CT scan data. These models were embedded in head models that include monopolar return electrodes in accurate anatomic positions. Potential distributions and neural excitation patterns were predicted for each of the models. RESULTS Modeled potential distributions and neural excitation profiles (threshold amplitudes, center frequencies, and bandwidths) are affected by user-specific cochlear morphology and electrode placement within the cochlea. CONCLUSIONS This work suggests that the use of user-specific models is indicated when more detailed analysis is required than what is available from generic models. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- T K Malherbe
- Department of Electrical, Electronic and Computer Engineering, Bioengineering Group, University of Pretoria, Lynnwood Road, Pretoria, Gauteng, 0002, South Africa
| | - T Hanekom
- Department of Electrical, Electronic and Computer Engineering, Bioengineering Group, University of Pretoria, Lynnwood Road, Pretoria, Gauteng, 0002, South Africa
| | - J J Hanekom
- Department of Electrical, Electronic and Computer Engineering, Bioengineering Group, University of Pretoria, Lynnwood Road, Pretoria, Gauteng, 0002, South Africa
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