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Pastore MT, Pulling KR, Chen C, Yost WA, Dorman MF. Synchronizing Automatic Gain Control in Bilateral Cochlear Implants Mitigates Dynamic Localization Deficits Introduced by Independent Bilateral Compression. Ear Hear 2024:00003446-990000000-00262. [PMID: 38472134 DOI: 10.1097/aud.0000000000001492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
OBJECTIVES The independence of left and right automatic gain controls (AGCs) used in cochlear implants can distort interaural level differences and thereby compromise dynamic sound source localization. We assessed the degree to which synchronizing left and right AGCs mitigates those difficulties as indicated by listeners' ability to use the changes in interaural level differences that come with head movements to avoid front-back reversals (FBRs). DESIGN Broadband noise stimuli were presented from one of six equally spaced loudspeakers surrounding the listener. Sound source identification was tested for stimuli presented at 70 dBA (above AGC threshold) for 10 bilateral cochlear implant patients, under conditions where (1) patients remained stationary and (2) free head movements within ±30° were encouraged. These conditions were repeated for both synchronized and independent AGCs. The same conditions were run at 50 dBA, below the AGC threshold, to assess listeners' baseline performance when AGCs were not engaged. In this way, the expected high variability in listener performance could be separated from effects of independent AGCs to reveal the degree to which synchronizing AGCs could restore localization performance to what it was without AGC compression. RESULTS The mean rate of FBRs was higher for sound stimuli presented at 70 dBA with independent AGCs, both with and without head movements, than at 50 dBA, suggesting that when AGCs were independently engaged they contributed to poorer front-back localization. When listeners remained stationary, synchronizing AGCs did not significantly reduce the rate of FBRs. When AGCs were independent at 70 dBA, head movements did not have a significant effect on the rate of FBRs. Head movements did have a significant group effect on the rate of FBRs at 50 dBA when AGCs were not engaged and at 70 dBA when AGCs were synchronized. Synchronization of AGCs, together with head movements, reduced the rate of FBRs to approximately what it was in the 50-dBA baseline condition. Synchronizing AGCs also had a significant group effect on listeners' overall percent correct localization. CONCLUSIONS Synchronizing AGCs allowed for listeners to mitigate front-back confusions introduced by unsynchronized AGCs when head motion was permitted, returning individual listener performance to roughly what it was in the 50-dBA baseline condition when AGCs were not engaged. Synchronization of AGCs did not overcome localization deficiencies which were observed when AGCs were not engaged, and which are therefore unrelated to AGC compression.
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Affiliation(s)
- M Torben Pastore
- College of Health Solutions, Arizona State University, Tempe, Arizona, USA
| | - Kathryn R Pulling
- College of Health Solutions, Arizona State University, Tempe, Arizona, USA
| | - Chen Chen
- Advanced Bionics, Valencia, California, USA
| | - William A Yost
- College of Health Solutions, Arizona State University, Tempe, Arizona, USA
| | - Michael F Dorman
- College of Health Solutions, Arizona State University, Tempe, Arizona, USA
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Valzolgher C, Bouzaid S, Grenouillet S, Gatel J, Ratenet L, Murenu F, Verdelet G, Salemme R, Gaveau V, Coudert A, Hermann R, Truy E, Farnè A, Pavani F. Training spatial hearing in unilateral cochlear implant users through reaching to sounds in virtual reality. Eur Arch Otorhinolaryngol 2023; 280:3661-3672. [PMID: 36905419 PMCID: PMC10313844 DOI: 10.1007/s00405-023-07886-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 02/13/2023] [Indexed: 03/12/2023]
Abstract
BACKGROUND AND PURPOSE Use of unilateral cochlear implant (UCI) is associated with limited spatial hearing skills. Evidence that training these abilities in UCI user is possible remains limited. In this study, we assessed whether a Spatial training based on hand-reaching to sounds performed in virtual reality improves spatial hearing abilities in UCI users METHODS: Using a crossover randomized clinical trial, we compared the effects of a Spatial training protocol with those of a Non-Spatial control training. We tested 17 UCI users in a head-pointing to sound task and in an audio-visual attention orienting task, before and after each training. Study is recorded in clinicaltrials.gov (NCT04183348). RESULTS During the Spatial VR training, sound localization errors in azimuth decreased. Moreover, when comparing head-pointing to sounds before vs. after training, localization errors decreased after the Spatial more than the control training. No training effects emerged in the audio-visual attention orienting task. CONCLUSIONS Our results showed that sound localization in UCI users improves during a Spatial training, with benefits that extend also to a non-trained sound localization task (generalization). These findings have potentials for novel rehabilitation procedures in clinical contexts.
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Affiliation(s)
- Chiara Valzolgher
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Corso Bettini, 31 Rovereto, Trento, Italy.
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France.
| | - Sabrina Bouzaid
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
| | - Solene Grenouillet
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
| | | | | | - Francesca Murenu
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
| | - Grégoire Verdelet
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
- Neuroimmersion, Lyon, France
| | - Romeo Salemme
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
- Neuroimmersion, Lyon, France
| | - Valérie Gaveau
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
| | | | | | - Eric Truy
- Hospices Civils de Lyon, Lyon, France
| | - Alessandro Farnè
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
- Neuroimmersion, Lyon, France
| | - Francesco Pavani
- Center for Mind/Brain Sciences (CIMeC), University of Trento, Corso Bettini, 31 Rovereto, Trento, Italy
- Integrative, Multisensory, Perception, Action and Cognition Team (IMPACT), Lyon Neuroscience Research Center, University of Lyon 1, Lyon, France
- Centro Interuniversitario di Ricerca "Cognizione, Linguaggio e Sordità" (CIRCLeS), Trento, Italy
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Valzolgher C, Gatel J, Bouzaid S, Grenouillet S, Todeschini M, Verdelet G, Salemme R, Gaveau V, Truy E, Farnè A, Pavani F. Reaching to Sounds Improves Spatial Hearing in Bilateral Cochlear Implant Users. Ear Hear 2023; 44:189-98. [PMID: 35982520 DOI: 10.1097/AUD.0000000000001267] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVES We assessed if spatial hearing training improves sound localization in bilateral cochlear implant (BCI) users and whether its benefits can generalize to untrained sound localization tasks. DESIGN In 20 BCI users, we assessed the effects of two training procedures (spatial versus nonspatial control training) on two different tasks performed before and after training (head-pointing to sound and audiovisual attention orienting). In the spatial training, participants identified sound position by reaching toward the sound sources with their hand. In the nonspatial training, comparable reaching movements served to identify sound amplitude modulations. A crossover randomized design allowed comparison of training procedures within the same participants. Spontaneous head movements while listening to the sounds were allowed and tracked to correlate them with localization performance. RESULTS During spatial training, BCI users reduced their sound localization errors in azimuth and adapted their spontaneous head movements as a function of sound eccentricity. These effects generalized to the head-pointing sound localization task, as revealed by greater reduction of sound localization error in azimuth and more accurate first head-orienting response, as compared to the control nonspatial training. BCI users benefited from auditory spatial cues for orienting visual attention, but the spatial training did not enhance this multisensory attention ability. CONCLUSIONS Sound localization in BCI users improves with spatial reaching-to-sound training, with benefits to a nontrained sound localization task. These findings pave the way to novel rehabilitation procedures in clinical contexts.
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Coudert A, Verdelet G, Reilly KT, Truy E, Gaveau V. Intensive Training of Spatial Hearing Promotes Auditory Abilities of Bilateral Cochlear Implant Adults: A Pilot Study. Ear Hear 2023; 44:61-76. [PMID: 35943235 DOI: 10.1097/AUD.0000000000001256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVE The aim of this study was to evaluate the feasibility of a virtual reality-based spatial hearing training protocol in bilateral cochlear implant (CI) users and to provide pilot data on the impact of this training on different qualities of hearing. DESIGN Twelve bilateral CI adults aged between 19 and 69 followed an intensive 10-week rehabilitation program comprised eight virtual reality training sessions (two per week) interspersed with several evaluation sessions (2 weeks before training started, after four and eight training sessions, and 1 month after the end of training). During each 45-minute training session, participants localized a sound source whose position varied in azimuth and/or in elevation. At the start of each trial, CI users received no information about sound location, but after each response, feedback was given to enable error correction. Participants were divided into two groups: a multisensory feedback group (audiovisual spatial cue) and an unisensory group (visual spatial cue) who only received feedback in a wholly intact sensory modality. Training benefits were measured at each evaluation point using three tests: 3D sound localization in virtual reality, the French Matrix test, and the Speech, Spatial and other Qualities of Hearing questionnaire. RESULTS The training was well accepted and all participants attended the whole rehabilitation program. Four training sessions spread across 2 weeks were insufficient to induce significant performance changes, whereas performance on all three tests improved after eight training sessions. Front-back confusions decreased from 32% to 14.1% ( p = 0.017); speech recognition threshold score from 1.5 dB to -0.7 dB signal-to-noise ratio ( p = 0.029) and eight CI users successfully achieved a negative signal-to-noise ratio. One month after the end of structured training, these performance improvements were still present, and quality of life was significantly improved for both self-reports of sound localization (from 5.3 to 6.7, p = 0.015) and speech understanding (from 5.2 to 5.9, p = 0.048). CONCLUSIONS This pilot study shows the feasibility and potential clinical relevance of this type of intervention involving a sensorial immersive environment and could pave the way for more systematic rehabilitation programs after cochlear implantation.
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Mertens G, Andries E, Kurz A, Tȧvora-Vieira D, Calvino M, Amann E, Anderson I, Lorens A. Towards a Consensus on an ICF-Based Classification System for Horizontal Sound-Source Localization. J Pers Med 2022; 12. [PMID: 36556192 DOI: 10.3390/jpm12121971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 11/15/2022] [Accepted: 11/18/2022] [Indexed: 12/05/2022] Open
Abstract
The study aimed to develop a consensus classification system for the reporting of sound localization testing results, especially in the field of cochlear implantation. Against the background of an overview of the wide variations present in localization testing procedures and reporting metrics, a novel classification system was proposed to report localization errors according to the widely accepted International Classification of Functioning, Disability and Health (ICF) framework. The obtained HEARRING_LOC_ICF scale includes the ICF graded scale: 0 (no impairment), 1 (mild impairment), 2 (moderate impairment), 3 (severe impairment), and 4 (complete impairment). Improvement of comparability of localization results across institutes, localization testing setups, and listeners was demonstrated by applying the classification system retrospectively to data obtained from cohorts of normal-hearing and cochlear implant listeners at our institutes. The application of our classification system will help to facilitate multi-center studies, as well as allowing better meta-analyses of data, resulting in improved evidence-based practice in the field.
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Gessa E, Giovanelli E, Spinella D, Verdelet G, Farnè A, Frau GN, Pavani F, Valzolgher C. Spontaneous head-movements improve sound localization in aging adults with hearing loss. Front Hum Neurosci 2022; 16:1026056. [PMID: 36310849 PMCID: PMC9609159 DOI: 10.3389/fnhum.2022.1026056] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 09/21/2022] [Indexed: 11/04/2023] Open
Abstract
Moving the head while a sound is playing improves its localization in human listeners, in children and adults, with or without hearing problems. It remains to be ascertained if this benefit can also extend to aging adults with hearing-loss, a population in which spatial hearing difficulties are often documented and intervention solutions are scant. Here we examined performance of elderly adults (61-82 years old) with symmetrical or asymmetrical age-related hearing-loss, while they localized sounds with their head fixed or free to move. Using motion-tracking in combination with free-field sound delivery in visual virtual reality, we tested participants in two auditory spatial tasks: front-back discrimination and 3D sound localization in front space. Front-back discrimination was easier for participants with symmetrical compared to asymmetrical hearing-loss, yet both groups reduced their front-back errors when head-movements were allowed. In 3D sound localization, free head-movements reduced errors in the horizontal dimension and in a composite measure that computed errors in 3D space. Errors in 3D space improved for participants with asymmetrical hearing-impairment when the head was free to move. These preliminary findings extend to aging adults with hearing-loss the literature on the advantage of head-movements on sound localization, and suggest that the disparity of auditory cues at the two ears can modulate this benefit. These results point to the possibility of taking advantage of self-regulation strategies and active behavior when promoting spatial hearing skills.
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Affiliation(s)
- Elena Gessa
- Center for Mind/Brian Sciences - CIMeC, University of Trento, Rovereto, Italy
| | - Elena Giovanelli
- Center for Mind/Brian Sciences - CIMeC, University of Trento, Rovereto, Italy
| | | | - Grégoire Verdelet
- Integrative, Multisensory, Perception, Action and Cognition Team-IMPACT, Centre de Recherche en Neuroscience de Lyon, University Lyon 1, Lyon, France
- Neuro-immersion, Centre de Recherche en Neuroscience de Lyon, Lyon, France
| | - Alessandro Farnè
- Center for Mind/Brian Sciences - CIMeC, University of Trento, Rovereto, Italy
- Integrative, Multisensory, Perception, Action and Cognition Team-IMPACT, Centre de Recherche en Neuroscience de Lyon, University Lyon 1, Lyon, France
- Neuro-immersion, Centre de Recherche en Neuroscience de Lyon, Lyon, France
| | | | - Francesco Pavani
- Center for Mind/Brian Sciences - CIMeC, University of Trento, Rovereto, Italy
- Integrative, Multisensory, Perception, Action and Cognition Team-IMPACT, Centre de Recherche en Neuroscience de Lyon, University Lyon 1, Lyon, France
| | - Chiara Valzolgher
- Center for Mind/Brian Sciences - CIMeC, University of Trento, Rovereto, Italy
- Integrative, Multisensory, Perception, Action and Cognition Team-IMPACT, Centre de Recherche en Neuroscience de Lyon, University Lyon 1, Lyon, France
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Gaveau V, Coudert A, Salemme R, Koun E, Desoche C, Truy E, Farnè A, Pavani F. Benefits of active listening during 3D sound localization. Exp Brain Res 2022; 240:2817-2833. [PMID: 36071210 PMCID: PMC9587935 DOI: 10.1007/s00221-022-06456-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 08/28/2022] [Indexed: 11/29/2022]
Abstract
In everyday life, sound localization entails more than just the extraction and processing of auditory cues. When determining sound position in three dimensions, the brain also considers the available visual information (e.g., visual cues to sound position) and resolves perceptual ambiguities through active listening behavior (e.g., spontaneous head movements while listening). Here, we examined to what extent spontaneous head movements improve sound localization in 3D—azimuth, elevation, and depth—by comparing static vs. active listening postures. To this aim, we developed a novel approach to sound localization based on sounds delivered in the environment, brought into alignment thanks to a VR system. Our system proved effective for the delivery of sounds at predetermined and repeatable positions in 3D space, without imposing a physically constrained posture, and with minimal training. In addition, it allowed measuring participant behavior (hand, head and eye position) in real time. We report that active listening improved 3D sound localization, primarily by ameliorating accuracy and variability of responses in azimuth and elevation. The more participants made spontaneous head movements, the better was their 3D sound localization performance. Thus, we provide proof of concept of a novel approach to the study of spatial hearing, with potentials for clinical and industrial applications.
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Affiliation(s)
- V Gaveau
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France. .,University of Lyon 1, Lyon, France.
| | - A Coudert
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,ENT Departments, Hôpital Femme-Mère-Enfant and Edouard Herriot University Hospitals, Lyon, France
| | - R Salemme
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,Neuro-immersion, Lyon, France
| | - E Koun
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France
| | - C Desoche
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,Neuro-immersion, Lyon, France
| | - E Truy
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,ENT Departments, Hôpital Femme-Mère-Enfant and Edouard Herriot University Hospitals, Lyon, France
| | - A Farnè
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,Neuro-immersion, Lyon, France
| | - F Pavani
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, INSERM U1028, CNRS U5292, 16 Av. Doyen Lépine, BRON cedex, 69500, Lyon, France.,University of Lyon 1, Lyon, France.,Center for Mind/Brain Sciences - CIMeC, University of Trento, Rovereto, Italy
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Pastore MT, Natale SJ, Clayton C, Dorman MF, Yost WA, Zhou Y. Effects of Head Movements on Sound-Source Localization in Single-Sided Deaf Patients With Their Cochlear Implant On Versus Off. Ear Hear 2021; 41:1660-1674. [PMID: 33136640 PMCID: PMC7772279 DOI: 10.1097/aud.0000000000000882] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES We investigated the ability of single-sided deaf listeners implanted with a cochlear implant (SSD-CI) to (1) determine the front-back and left-right location of sound sources presented from loudspeakers surrounding the listener and (2) use small head rotations to further improve their localization performance. The resulting behavioral data were used for further analyses investigating the value of so-called "monaural" spectral shape cues for front-back sound source localization. DESIGN Eight SSD-CI patients were tested with their cochlear implant (CI) on and off. Eight normal-hearing (NH) listeners, with one ear plugged during the experiment, and another group of eight NH listeners, with neither ear plugged, were also tested. Gaussian noises of 3-sec duration were band-pass filtered to 2-8 kHz and presented from 1 of 6 loudspeakers surrounding the listener, spaced 60° apart. Perceived sound source localization was tested under conditions where the patients faced forward with the head stationary, and under conditions where they rotated their heads between (Equation is included in full-text article.). RESULTS (1) Under stationary listener conditions, unilaterally-plugged NH listeners and SSD-CI listeners (with their CIs both on and off) were nearly at chance in determining the front-back location of high-frequency sound sources. (2) Allowing rotational head movements improved performance in both the front-back and left-right dimensions for all listeners. (3) For SSD-CI patients with their CI turned off, head rotations substantially reduced front-back reversals, and the combination of turning on the CI with head rotations led to near-perfect resolution of front-back sound source location. (4) Turning on the CI also improved left-right localization performance. (5) As expected, NH listeners with both ears unplugged localized to the correct front-back and left-right hemifields both with and without head movements. CONCLUSIONS Although SSD-CI listeners demonstrate a relatively poor ability to distinguish the front-back location of sound sources when their head is stationary, their performance is substantially improved with head movements. Most of this improvement occurs when the CI is off, suggesting that the NH ear does most of the "work" in this regard, though some additional gain is introduced with turning the CI on. During head turns, these listeners appear to primarily rely on comparing changes in head position to changes in monaural level cues produced by the direction-dependent attenuation of high-frequency sounds that result from acoustic head shadowing. In this way, SSD-CI listeners overcome limitations to the reliability of monaural spectral and level cues under stationary conditions. SSD-CI listeners may have learned, through chronic monaural experience before CI implantation, or with the relatively impoverished spatial cues provided by their CI-implanted ear, to exploit the monaural level cue. Unilaterally-plugged NH listeners were also able to use this cue during the experiment to realize approximately the same magnitude of benefit from head turns just minutes after plugging, though their performance was less accurate than that of the SSD-CI listeners, both with and without their CI turned on.
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Affiliation(s)
- M Torben Pastore
- College of Health Solutions, Arizona State University, Tempe, Arizona, USA
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Pastore MT, Pulling KR, Chen C, Yost WA, Dorman MF. Effects of Bilateral Automatic Gain Control Synchronization in Cochlear Implants With and Without Head Movements: Sound Source Localization in the Frontal Hemifield. J Speech Lang Hear Res 2021; 64:2811-2824. [PMID: 34100627 PMCID: PMC8632503 DOI: 10.1044/2021_jslhr-20-00493] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 12/31/2020] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
Purpose For bilaterally implanted patients, the automatic gain control (AGC) in both left and right cochlear implant (CI) processors is usually neither linked nor synchronized. At high AGC compression ratios, this lack of coordination between the two processors can distort interaural level differences, the only useful interaural difference cue available to CI patients. This study assessed the improvement, if any, in the utility of interaural level differences for sound source localization in the frontal hemifield when AGCs were synchronized versus independent and when listeners were stationary versus allowed to move their heads. Method Sound source identification of broadband noise stimuli was tested for seven bilateral CI patients using 13 loudspeakers in the frontal hemifield, under conditions where AGCs were linked and unlinked. For half the conditions, patients remained stationary; in the other half, they were encouraged to rotate or reorient their heads within a range of approximately ± 30° during sound presentation. Results In general, those listeners who already localized reasonably well with independent AGCs gained the least from AGC synchronization, perhaps because there was less room for improvement. Those listeners who performed worst with independent AGCs gained the most from synchronization. All listeners performed as well or better with synchronization than without; however, intersubject variability was high. Head movements had little impact on the effectiveness of synchronization of AGCs. Conclusion Synchronization of AGCs offers one promising strategy for improving localization performance in the frontal hemifield for bilaterally implanted CI patients. Supplemental Material https://doi.org/10.23641/asha.14681412.
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Coudert A, Gaveau V, Gatel J, Verdelet G, Salemme R, Farne A, Pavani F, Truy E. Spatial Hearing Difficulties in Reaching Space in Bilateral Cochlear Implant Children Improve With Head Movements. Ear Hear 2021; 43:192-205. [PMID: 34225320 PMCID: PMC8694251 DOI: 10.1097/aud.0000000000001090] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Supplemental Digital Content is available in the text. The aim of this study was to assess three-dimensional (3D) spatial hearing abilities in reaching space of children and adolescents fitted with bilateral cochlear implants (BCI). The study also investigated the impact of spontaneous head movements on sound localization abilities.
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Affiliation(s)
- Aurélie Coudert
- Integrative Multisensory Perception Action & Cognition Team-ImpAct, Lyon Neuroscience Research Center, Lyon, France Department of Pediatric Otolaryngology-Head & Neck Surgery, Femme Mere Enfant Hospital, Hospices Civils de Lyon, Lyon, France Department of Otolaryngology-Head & Neck Surgery, Edouard Herriot Hospital, Hospices Civils de Lyon, Lyon, France University of Lyon 1, Lyon, France Hospices Civils de Lyon, Neuro-immersion Platform, Lyon, France Center for Mind/Brain Sciences (CIMeC), University of Trento, Rovereto, Italy Department of Psychology and Cognitive Sciences, University of Trento, Rovereto, Italy
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Körtje M, Baumann U, Stöver T, Weissgerber T. Sensitivity to interaural time differences and localization accuracy in cochlear implant users with combined electric-acoustic stimulation. PLoS One 2020; 15:e0241015. [PMID: 33075114 PMCID: PMC7571672 DOI: 10.1371/journal.pone.0241015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/07/2020] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES In this study, localization accuracy and sensitivity to acoustic interaural time differences (ITDs) in subjects using cochlear implants with combined electric-acoustic stimulation (EAS) were assessed and compared with the results of a normal hearing control group. METHODS Eight CI users with EAS (2 bilaterally implanted, 6 unilaterally implanted) and symmetric binaural acoustic hearing and 24 normal hearing subjects participated in the study. The first experiment determined mean localization error (MLE) for different angles of sound incidence between ± 60° (frontal and dorsal presentation). The stimuli were either low-pass, high-pass or broadband noise bursts. In a second experiment, just noticeable differences (JND) of ITDs were measured for pure tones of 125 Hz, 250 Hz and 500 Hz (headphone presentation). RESULTS Experiment 1: MLE of EAS subjects was 8.5°, 14.3° and 14.7°, (low-, high-pass and broadband stimuli respectively). In the control group, MLE was 1.8° (broadband stimuli). In the differentiation between sound incidence from front and back, EAS subjects performed on chance level. Experiment 2: The JND-ITDs were 88.7 μs for 125 Hz, 48.8 μs for 250 Hz and 52.9 μs for 500 Hz (EAS subjects). Compared to the control group, JND-ITD for 125 Hz was on the same level of performance. No statistically significant correlation was found between MLE and JND-ITD in the EAS cohort. CONCLUSIONS Near to normal ITD sensitivity in the lower frequency acoustic hearing was demonstrated in a cohort of EAS users. However, in an acoustic localization task, the majority of the subjects did not reached the level of accuracy of normal hearing. Presumably, signal processing time delay differences between devices used on both sides are deteriorating the transfer of precise binaural timing cues.
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Affiliation(s)
- Monika Körtje
- Audiological Acoustics, ENT Department, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Uwe Baumann
- Audiological Acoustics, ENT Department, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Timo Stöver
- ENT Department, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Tobias Weissgerber
- Audiological Acoustics, ENT Department, University Hospital Frankfurt, Goethe University Frankfurt, Frankfurt am Main, Germany
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Abstract
Adaptation to systematic visual distortions is well-documented but there is little evidence of similar adaptation to radical changes in audition. We use a pseudophone to transpose the sound streams arriving at the left and right ears, evaluating the perceptual effects it provokes and the possibility of learning to locate sounds in the reversed condition. Blindfolded participants remain seated at the center of a semicircular arrangement of 7 speakers and are asked to orient their head towards a sound source. We postulate that a key factor underlying adaptation is the self-generated activity that allows participants to learn new sensorimotor schemes. We investigate passive listening conditions (very short duration stimulus not permitting active exploration) and dynamic conditions (continuous stimulus allowing participants time to freely move their heads or remain still). We analyze head movement kinematics, localization errors, and qualitative reports. Results show movement-induced perceptual disruptions in the dynamic condition with static sound sources displaying apparent movement. This effect is reduced after a short training period and participants learn to find sounds in a left-right reversed field for all but the extreme lateral positions where motor patterns are more restricted. Strategies become less exploratory and more direct with training. Results support the hypothesis that self-generated movements underlie adaptation to radical sensorimotor distortions.
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Affiliation(s)
- Fernando Bermejo
- Centro de Investigación y Transferencia en Acústica, Universidad Tecnológica Nacional - Facultad Regional Córdoba, CONICET, CP 5016, Córdoba, Argentina.
- Facultad de Psicología, Universidad Nacional de Córdoba, CP 5016, Córdoba, Argentina.
| | - Ezequiel A Di Paolo
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
- IAS-Research Center for Life, Mind, and Society, University of the Basque Country, San Sebastián, Spain
- Centre for Computational Neuroscience and Robotics, University of Sussex, Brighton, UK
| | - L Guillermo Gilberto
- Centro de Investigación y Transferencia en Acústica, Universidad Tecnológica Nacional - Facultad Regional Córdoba, CONICET, CP 5016, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Valentín Lunati
- Centro de Investigación y Transferencia en Acústica, Universidad Tecnológica Nacional - Facultad Regional Córdoba, CONICET, CP 5016, Córdoba, Argentina
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - M Virginia Barrios
- Centro de Investigación y Transferencia en Acústica, Universidad Tecnológica Nacional - Facultad Regional Córdoba, CONICET, CP 5016, Córdoba, Argentina
- Facultad de Psicología, Universidad Nacional de Córdoba, CP 5016, Córdoba, Argentina
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Archer-Boyd AW, Carlyon RP. Simulations of the effect of unlinked cochlear-implant automatic gain control and head movement on interaural level differences. J Acoust Soc Am 2019; 145:1389. [PMID: 31067937 PMCID: PMC6711771 DOI: 10.1121/1.5093623] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/22/2019] [Indexed: 05/31/2023]
Abstract
This study simulated the effect of unlinked automatic gain control (AGC) and head movement on the output levels and resulting inter-aural level differences (ILDs) produced by bilateral cochlear implant (CI) processors. The angular extent and velocity of the head movements were varied in order to observe the interaction between unlinked AGC and head movement. Static, broadband input ILDs were greatly reduced by the high-ratio, slow-time-constant AGC used. The size of head-movement-induced dynamic ILDs depended more on the velocity and angular extent of the head movement than on the angular position of the source. The profiles of the dynamic, broadband output ILDs were very different from the dynamic, broadband input ILD profiles. Short-duration, high-velocity head movements resulted in dynamic output ILDs that continued to change after head movement had stopped. Analysis of narrowband, single-channel ILDs showed that static output ILDs were reduced across all frequencies, producing low-frequency ILDs of the opposite sign to the high-frequency ILDs. During head movements, low- and high-frequency ILDs also changed with opposite sign. The results showed that the ILDs presented to bilateral CI listeners during head turns were highly distorted by the interaction of the bilateral, unlinked AGC and the level changes induced by head movement.
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Affiliation(s)
- Alan W Archer-Boyd
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, United Kingdom
| | - Robert P Carlyon
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, United Kingdom
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