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Lambriks L, van Hoof M, Debruyne J, Janssen M, Chalupper J, van der Heijden K, Hof J, Hellingman K, Devocht E, George E. Imaging-based frequency mapping for cochlear implants - Evaluated using a daily randomized controlled trial. Front Neurosci 2023; 17:1119933. [PMID: 37123376 PMCID: PMC10133468 DOI: 10.3389/fnins.2023.1119933] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 03/03/2023] [Indexed: 05/02/2023] Open
Abstract
Background Due to variation in electrode design, insertion depth and cochlear morphology, patients with a cochlear implant (CI) often have to adapt to a substantial mismatch between the characteristic response frequencies of cochlear neurons and the stimulus frequencies assigned to electrode contacts. We introduce an imaging-based fitting intervention, which aimed to reduce frequency-to-place mismatch by aligning frequency mapping with the tonotopic position of electrodes. Results were evaluated in a novel trial set-up where subjects crossed over between intervention and control using a daily within-patient randomized approach, immediately from the start of CI rehabilitation. Methods Fourteen adult participants were included in this single-blinded, daily randomized clinical trial. Based on a fusion of pre-operative imaging and a post-operative cone beam CT scan (CBCT), mapping of electrical input was aligned to natural place-pitch arrangement in the individual cochlea. That is, adjustments to the CI's frequency allocation table were made so electrical stimulation of frequencies matched as closely as possible with corresponding acoustic locations in the cochlea. For a period of three months, starting at first fit, a scheme was implemented whereby the blinded subject crossed over between the experimental and standard fitting program using a daily randomized wearing schedule, and thus effectively acted as their own control. Speech outcomes (such as speech intelligibility in quiet and noise, sound quality and listening effort) were measured with both settings throughout the study period. Results On a group level, standard fitting obtained subject preference and showed superior results in all outcome measures. In contrast, two out of fourteen subjects preferred the imaging-based fitting and correspondingly had better speech understanding with this setting compared to standard fitting. Conclusion On average, cochlear implant fitting based on individual tonotopy did not elicit higher speech intelligibility but variability in individual results strengthen the potential for individualized frequency fitting. The novel trial design proved to be a suitable method for evaluation of experimental interventions in a prospective trial setup with cochlear implants.
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Affiliation(s)
- Lars Lambriks
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Marc van Hoof
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Joke Debruyne
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Miranda Janssen
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
- Department of Methodology and Statistics, Care and Public Health Research Institute, Maastricht University, Maastricht, Netherlands
| | - Josef Chalupper
- Advanced Bionics European Research Centre, Hannover, Germany
| | - Kiki van der Heijden
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Janny Hof
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Katja Hellingman
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Elke Devocht
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
| | - Erwin George
- Department of ENT/Audiology, School for Mental Health and Neuroscience, Maastricht University Medical Centre, Maastricht, Netherlands
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Saadoun A, Schein A, Péan V, Legrand P, Aho Glélé LS, Bozorg Grayeli A. Frequency Fitting Optimization Using Evolutionary Algorithm in Cochlear Implant Users with Bimodal Binaural Hearing. Brain Sci 2022; 12:brainsci12020253. [PMID: 35204015 PMCID: PMC8870060 DOI: 10.3390/brainsci12020253] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 02/04/2023] Open
Abstract
Optimizing hearing in patients with a unilateral cochlear implant (CI) and contralateral acoustic hearing is a challenge. Evolutionary algorithms (EA) can explore a large set of potential solutions in a stochastic manner to approach the optimum of a minimization problem. The objective of this study was to develop and evaluate an EA-based protocol to modify the default frequency settings of a MAP (fMAP) of the CI in patients with bimodal hearing. Methods: This monocentric prospective study included 27 adult CI users (with post-lingual deafness and contralateral functional hearing). A fitting program based on EA was developed to approach the best fMAP. Generated fMAPs were tested by speech recognition (word recognition score, WRS) in noise and free-field-like conditions. By combining these first fMAPs and adding some random changes, a total of 13 fMAPs over 3 generations were produced. Participants were evaluated before and 45 to 60 days after the fitting by WRS in noise and questionnaires on global sound quality and music perception in bimodal binaural conditions. Results: WRS in noise improved with the EA-based fitting in comparison to the default fMAP (41.67 ± 9.70% versus 64.63 ± 16.34%, respectively, p = 0.0001, signed-rank test). The global sound quality and music perception were also improved, as judged by ratings on questionnaires and scales. Finally, most patients chose to keep the new fitting definitively. Conclusions: By modifying the default fMAPs, the EA improved the speech discrimination in noise and the sound quality in bimodal binaural conditions.
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Affiliation(s)
- Alexis Saadoun
- Department of Otolaryngology—Head and Neck Surgery, Dijon University Hospital, 21000 Dijon, France; (A.S.); (A.S.)
| | - Antoine Schein
- Department of Otolaryngology—Head and Neck Surgery, Dijon University Hospital, 21000 Dijon, France; (A.S.); (A.S.)
| | - Vincent Péan
- Clinical Support Department, MED-EL, 75012 Paris, France;
| | - Pierrick Legrand
- Institute of Mathematics of Bordeaux, UMR CNRS 5251, ASTRAL Team, Inria Bordeaux Sud-Ouest, University of Bordeaux, 33405 Talence, France;
| | - Ludwig Serge Aho Glélé
- Department of Hospital Epidemiology and Infection Control, Dijon University Hospital, 21000 Dijon, France;
| | - Alexis Bozorg Grayeli
- Department of Otolaryngology—Head and Neck Surgery, Dijon University Hospital, 21000 Dijon, France; (A.S.); (A.S.)
- ImVia Research Laboratory, Bourgogne-Franche Comté University, 21000 Dijon, France
- Correspondence:
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Nogueira W, Boghdady NE, Langner F, Gaudrain E, Başkent D. Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users. Trends Hear 2021; 25:23312165211030166. [PMID: 34461780 PMCID: PMC8411629 DOI: 10.1177/23312165211030166] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 11/16/2022] Open
Abstract
Speech intelligibility in multitalker settings is challenging for most cochlear implant (CI) users. One possibility for this limitation is the suboptimal representation of vocal cues in implant processing, such as the fundamental frequency (F0), and the vocal tract length (VTL). Previous studies suggested that while F0 perception depends on spectrotemporal cues, VTL perception relies largely on spectral cues. To investigate how spectral smearing in CIs affects vocal cue perception in speech-on-speech (SoS) settings, adjacent electrodes were simultaneously stimulated using current steering in 12 Advanced Bionics users to simulate channel interaction. In current steering, two adjacent electrodes are simultaneously stimulated forming a channel of parallel stimulation. Three such stimulation patterns were used: Sequential (one current steering channel), Paired (two channels), and Triplet stimulation (three channels). F0 and VTL just-noticeable differences (JNDs; Task 1), in addition to SoS intelligibility (Task 2) and comprehension (Task 3), were measured for each stimulation strategy. In Tasks 2 and 3, four maskers were used: the same female talker, a male voice obtained by manipulating both F0 and VTL (F0+VTL) of the original female speaker, a voice where only F0 was manipulated, and a voice where only VTL was manipulated. JNDs were measured relative to the original voice for the F0, VTL, and F0+VTL manipulations. When spectral smearing was increased from Sequential to Triplet, a significant deterioration in performance was observed for Tasks 1 and 2, with no differences between Sequential and Paired stimulation. Data from Task 3 were inconclusive. These results imply that CI users may tolerate certain amounts of channel interaction without significant reduction in performance on tasks relying on voice perception. This points to possibilities for using parallel stimulation in CIs for reducing power consumption.
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Affiliation(s)
- Waldo Nogueira
- Department of Otolaryngology, Medical University
Hannover and Cluster of Excellence Hearing4all, Hanover, Germany
| | - Nawal El Boghdady
- Department of Otorhinolaryngology, University Medical
Center Groningen, University of Groningen, Groningen,
Netherlands
- Research School of Behavioral and Cognitive
Neurosciences, University of
Groningen, University of Groningen, Groningen,
Netherlands
| | - Florian Langner
- Department of Otolaryngology, Medical University
Hannover and Cluster of Excellence Hearing4all, Hanover, Germany
| | - Etienne Gaudrain
- Department of Otorhinolaryngology, University Medical
Center Groningen, University of Groningen, Groningen,
Netherlands
- Research School of Behavioral and Cognitive
Neurosciences, University of
Groningen, University of Groningen, Groningen,
Netherlands
- Lyon Neuroscience Research Center, CNRS UMR 5292,
INSERM U1028, University Lyon 1, Lyon, France
| | - Deniz Başkent
- Department of Otorhinolaryngology, University Medical
Center Groningen, University of Groningen, Groningen,
Netherlands
- Research School of Behavioral and Cognitive
Neurosciences, University of
Groningen, University of Groningen, Groningen,
Netherlands
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Grasmeder ML, Verschuur CA, van Besouw RM, Wheatley AMH, Newman TA. Measurement of pitch perception as a function of cochlear implant electrode and its effect on speech perception with different frequency allocations. Int J Audiol 2018; 58:158-166. [PMID: 30370800 DOI: 10.1080/14992027.2018.1516048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
OBJECTIVE An experiment was conducted to investigate the possibility that speech perception could be improved for some cochlear implant (CI) users by adjustment of the frequency allocation to the electrodes, following assessment of pitch perception along the electrode array. STUDY SAMPLE Thirteen adult CI users with MED-EL devices participated in the study. DESIGN Pitch perception was assessed for individual CI electrode pairs using the Pitch Contour Test (PCT), giving information on pitch discrimination and pitch ranking for adjacent electrodes. Sentence perception in noise was also assessed with ten different frequency allocations, including the default. RESULTS Pitch perception was found to be poorer for both discrimination and ranking scores at either end of the electrode array. A significant effect of frequency allocation was found for sentence scores [F(4.24,38.2) = 7.14, p < 0.001] and a significant interaction between sentence score and PCT ranking score for basal electrodes was found [F(4.24,38.2) = 2.95, p = 0.03]. Participants with poorer pitch perception at the basal end had poorer scores for some allocations with greater basal shift. CONCLUSIONS The results suggest that speech perception could be improved for CI users by assessment of pitch perception using the PCT and subsequent adjustment of pitch-related stimulation parameters.
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Affiliation(s)
- M L Grasmeder
- a Auditory Implant Service University of Southampton , Southampton , UK
| | - C A Verschuur
- a Auditory Implant Service University of Southampton , Southampton , UK
| | - R M van Besouw
- b Institute of Sound and Vibration Research, University of Southampton , UK
| | - A M H Wheatley
- b Institute of Sound and Vibration Research, University of Southampton , UK
| | - T A Newman
- c Southampton Neuroscience Group , University of Southampton , UK
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El Boghdady N, Başkent D, Gaudrain E. Effect of frequency mismatch and band partitioning on vocal tract length perception in vocoder simulations of cochlear implant processing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 143:3505. [PMID: 29960490 DOI: 10.1121/1.5041261] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The vocal tract length (VTL) of a speaker is an important voice cue that aids speech intelligibility in multi-talker situations. However, cochlear implant (CI) users demonstrate poor VTL sensitivity. This may be partially caused by the mismatch between frequencies received by the implant and those corresponding to places of stimulation along the cochlea. This mismatch can distort formant spacing, where VTL cues are encoded. In this study, the effects of frequency mismatch and band partitioning on VTL sensitivity were investigated in normal hearing listeners with vocoder simulations of CI processing. The hypotheses were that VTL sensitivity may be reduced by increased frequency mismatch and insufficient spectral resolution in how the frequency range is partitioned, specifically where formants lie. Moreover, optimal band partitioning might mitigate the detrimental effects of frequency mismatch on VTL sensitivity. Results showed that VTL sensitivity decreased with increased frequency mismatch and reduced spectral resolution near the low frequencies of the band partitioning map. Band partitioning was independent of mismatch, indicating that if a given partitioning is suboptimal, a better partitioning might improve VTL sensitivity despite the degree of mismatch. These findings suggest that customizing the frequency partitioning map may enhance VTL perception in individual CI users.
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Affiliation(s)
- Nawal El Boghdady
- University of Groningen, University Medical Center Groningen, Department of Otorhinolaryngology/Head and Neck Surgery, Groningen, The Netherlands
| | - Deniz Başkent
- University of Groningen, University Medical Center Groningen, Department of Otorhinolaryngology/Head and Neck Surgery, Groningen, The Netherlands
| | - Etienne Gaudrain
- University of Groningen, University Medical Center Groningen, Department of Otorhinolaryngology/Head and Neck Surgery, Groningen, The Netherlands
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Brochier T, McDermott HJ, McKay CM. The effect of presentation level and stimulation rate on speech perception and modulation detection for cochlear implant users. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:4097. [PMID: 28618807 PMCID: PMC5457292 DOI: 10.1121/1.4983658] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 04/26/2017] [Accepted: 05/03/2017] [Indexed: 06/07/2023]
Abstract
In order to improve speech understanding for cochlear implant users, it is important to maximize the transmission of temporal information. The combined effects of stimulation rate and presentation level on temporal information transfer and speech understanding remain unclear. The present study systematically varied presentation level (60, 50, and 40 dBA) and stimulation rate [500 and 2400 pulses per second per electrode (pps)] in order to observe how the effect of rate on speech understanding changes for different presentation levels. Speech recognition in quiet and noise, and acoustic amplitude modulation detection thresholds (AMDTs) were measured with acoustic stimuli presented to speech processors via direct audio input (DAI). With the 500 pps processor, results showed significantly better performance for consonant-vowel nucleus-consonant words in quiet, and a reduced effect of noise on sentence recognition. However, no rate or level effect was found for AMDTs, perhaps partly because of amplitude compression in the sound processor. AMDTs were found to be strongly correlated with the effect of noise on sentence perception at low levels. These results indicate that AMDTs, at least when measured with the CP910 Freedom speech processor via DAI, explain between-subject variance of speech understanding, but do not explain within-subject variance for different rates and levels.
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Affiliation(s)
- Tim Brochier
- Department of Medical Bionics, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Hugh J McDermott
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Colette M McKay
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
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Grasmeder ML, Verschuur CA, Batty VB. Optimizing frequency-to-electrode allocation for individual cochlear implant users. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2014; 136:3313. [PMID: 25480076 DOI: 10.1121/1.4900831] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Individual adjustment of frequency-to-electrode assignment in cochlear implants (CIs) may potentially improve speech perception outcomes. Twelve adult CI users were recruited for an experiment, in which frequency maps were adjusted using insertion angles estimated from post-operative x rays; results were analyzed for ten participants with good quality x rays. The allocations were a mapping to the Greenwood function, a compressed map limited to the area containing spiral ganglion (SG) cells, a reduced frequency range map (RFR), and participants' clinical maps. A trial period of at least six weeks was given for the clinical, Greenwood, and SG maps although participants could return to their clinical map if they wished. Performance with the Greenwood map was poor for both sentence and vowel perception and correlated with insertion angle; performance with the SG map was poorer than for the clinical map. The RFR map was significantly better than the clinical map for three participants, for sentence perception, but worse for three others. Those with improved performance had relatively deep insertions and poor electrode discrimination ability for apical electrodes. The results suggest that CI performance could be improved by adjustment of the frequency allocation, based on a measure of insertion angle and/or electrode discrimination ability.
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Affiliation(s)
- Mary L Grasmeder
- Auditory Implant Service, Faculty of Engineering and the Environment, Building 19, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Carl A Verschuur
- Auditory Implant Service, Faculty of Engineering and the Environment, Building 19, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Vincent B Batty
- Wessex Neurological Centre, University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton SO16 6YD, United Kingdom
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Svirsky MA, Talavage TM, Sinha S, Neuburger H, Azadpour M. Gradual adaptation to auditory frequency mismatch. Hear Res 2014; 322:163-70. [PMID: 25445816 DOI: 10.1016/j.heares.2014.10.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/13/2014] [Accepted: 10/16/2014] [Indexed: 12/01/2022]
Abstract
What is the best way to help humans adapt to a distorted sensory input? Interest in this question is more than academic. The answer may help facilitate auditory learning by people who became deaf after learning language and later received a cochlear implant (a neural prosthesis that restores hearing through direct electrical stimulation of the auditory nerve). There is evidence that some cochlear implants (which provide information that is spectrally degraded to begin with) stimulate neurons with higher characteristic frequency than the acoustic frequency of the original stimulus. In other words, the stimulus is shifted in frequency with respect to what the listener expects to hear. This frequency misalignment may have a negative influence on speech perception by CI users. However, a perfect frequency-place alignment may result in the loss of important low frequency speech information. A trade-off may involve a gradual approach: start with correct frequency-place alignment to allow listeners to adapt to the spectrally degraded signal first, and then gradually increase the frequency shift to allow them to adapt to it over time. We used an acoustic model of a cochlear implant to measure adaptation to a frequency-shifted signal, using either the gradual approach or the "standard" approach (sudden imposition of the frequency shift). Listeners in both groups showed substantial auditory learning, as measured by increases in speech perception scores over the course of fifteen one-hour training sessions. However, the learning process was faster for listeners who were exposed to the gradual approach. These results suggest that gradual rather than sudden exposure may facilitate perceptual learning in the face of a spectrally degraded, frequency-shifted input. This article is part of a Special Issue entitled <Lasker Award>.
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Affiliation(s)
- Mario A Svirsky
- Dept. of Otolaryngology-HNS, New York University School of Medicine, New York, NY, USA; Center of Neural Science, New York University, New York, NY, USA.
| | - Thomas M Talavage
- ECE, Purdue University, West Lafayette, IN, USA; BME Depts., Purdue University, West Lafayette, IN, USA
| | | | - Heidi Neuburger
- Dept. of Otolaryngology-HNS, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Mahan Azadpour
- Dept. of Otolaryngology-HNS, New York University School of Medicine, New York, NY, USA
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Carlyon RP, Monstrey J, Deeks JM, Macherey O. Evaluation of a cochlear-implant processing strategy incorporating phantom stimulation and asymmetric pulses. Int J Audiol 2014; 53:871-9. [PMID: 25358027 PMCID: PMC4266076 DOI: 10.3109/14992027.2014.932024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE To evaluate a speech-processing strategy in which the lowest frequency channel is conveyed using an asymmetric pulse shape and "phantom stimulation", where current is injected into one intra-cochlear electrode and where the return current is shared between an intra-cochlear and an extra-cochlear electrode. This strategy is expected to provide more selective excitation of the cochlear apex, compared to a standard strategy where the lowest-frequency channel is conveyed by symmetric pulses in monopolar mode. In both strategies all other channels were conveyed by monopolar stimulation. DESIGN Within-subjects comparison between the two strategies. Four experiments: (1) discrimination between the strategies, controlling for loudness differences, (2) consonant identification, (3) recognition of lowpass-filtered sentences in quiet, (4) sentence recognition in the presence of a competing speaker. STUDY SAMPLE Eight users of the Advanced Bionics CII/Hi-Res 90k cochlear implant. RESULTS Listeners could easily discriminate between the two strategies but no consistent differences in performance were observed. CONCLUSIONS The proposed method does not improve speech perception, at least in the short term.
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Garadat SN, Zwolan TA, Pfingst BE. Using temporal modulation sensitivity to select stimulation sites for processor MAPs in cochlear implant listeners. Audiol Neurootol 2013; 18:247-60. [PMID: 23881208 DOI: 10.1159/000351302] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 03/29/2013] [Indexed: 11/19/2022] Open
Abstract
Previous studies in our laboratory showed that temporal acuity as assessed by modulation detection thresholds (MDTs) varied across activation sites and that this site-to-site variability was subject specific. Using two 10-channel MAPs, the previous experiments showed that processor MAPs that had better across-site mean (ASM) MDTs yielded better speech recognition than MAPs with poorer ASM MDTs tested in the same subject. The current study extends our earlier work on developing more optimal-fitting strategies to test the feasibility of using a site-selection approach in the clinical domain. This study examined the hypothesis that revising the clinical speech processor MAP for cochlear implant (CI) recipients by turning off selected sites that have poorer temporal acuity and reallocating frequencies to the remaining electrodes would lead to improved speech recognition. Twelve CI recipients participated in the experiments. We found that site selection procedure based on MDTs in the presence of a masker resulted in improved performance on consonant recognition and recognition of sentences in noise. In contrast, vowel recognition was poorer with the experimental MAP than with the clinical MAP, possibly due to reduced spectral resolution when sites were removed from the experimental MAP. Overall, these results suggest a promising path for improving recipient outcomes using personalized processor-fitting strategies based on a psychophysical measure of temporal acuity.
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Affiliation(s)
- Soha N Garadat
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI, USA.
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Cochlear Implantation in Unilateral Deaf Subjects Associated With Ipsilateral Tinnitus. Otol Neurotol 2010; 31:1381-5. [PMID: 20729788 DOI: 10.1097/mao.0b013e3181e3d353] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Goupell MJ, Laback B, Majdak P, Baumgartner WD. Effects of upper-frequency boundary and spectral warping on speech intelligibility in electrical stimulation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 123:2295-309. [PMID: 18397034 PMCID: PMC3061454 DOI: 10.1121/1.2831738] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Speech understanding was tested for seven listeners using 12-electrode Med-El cochlear implants (CIs) and six normal-hearing listeners using a CI simulation. Eighteen different types of processing were evaluated, which varied the frequency-to-tonotopic place mapping and the upper boundary of the frequency and stimulation range. Spectrally unwarped and warped conditions were included. Unlike previous studies on this topic, the lower boundary of the frequency and stimulation range was fixed while the upper boundary was varied. For the unwarped conditions, only eight to ten channels were needed in both quiet and noise to achieve no significant degradation in speech understanding compared to the normal 12-electrode speech processing. The unwarped conditions were often the best conditions for understanding speech; however, small changes in frequency-to-place mapping (<0.77 octaves for the most basal electrode) yielded no significant degradation in performance from the nearest unwarped condition. A second experiment measured the effect of feedback training for both the unwarped and warped conditions. Improvements were found for the unwarped and frequency-expanded conditions, but not for the compressed condition. These results have implications for new CI processing strategies, such as the inclusion of spectral localization cues.
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Affiliation(s)
- Matthew J Goupell
- Acoustics Research Institute, Austrian Academy of Sciences, Wohllebengasse 12-14, A-1040 Vienna, Austria.
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Li N, Loizou PC. A glimpsing account for the benefit of simulated combined acoustic and electric hearing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2008; 123:2287-2294. [PMID: 18397033 PMCID: PMC2677314 DOI: 10.1121/1.2839013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2007] [Revised: 11/29/2007] [Accepted: 01/08/2008] [Indexed: 05/25/2023]
Abstract
The benefits of combined electric and acoustic stimulation (EAS) in terms of speech recognition in noise are well established; however the underlying factors responsible for this benefit are not clear. The present study tests the hypothesis that having access to acoustic information in the low frequencies makes it easier for listeners to glimpse the target. Normal-hearing listeners were presented with vocoded speech alone (V), low-pass (LP) filtered speech alone, combined vocoded and LP speech (LP+V) and with vocoded stimuli constructed so that the low-frequency envelopes were easier to glimpse. Target speech was mixed with two types of maskers (steady-state noise and competing talker) at -5 to 5 dB signal-to-noise ratios. Results indicated no advantage of LP+V in steady noise, but a significant advantage over V in the competing talker background, an outcome consistent with the notion that it is easier for listeners to glimpse the target in fluctuating maskers. A significant improvement in performance was noted with the modified glimpsed stimuli over the original vocoded stimuli. These findings taken together suggest that a significant factor contributing to the EAS advantage is the enhanced ability to glimpse the target.
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Affiliation(s)
- Ning Li
- Department of Electrical Engineering, University of Texas at Dallas, Richardson, Texas 75083-0688, USA
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Smith MW, Faulkner A. Perceptual adaptation by normally hearing listeners to a simulated "hole" in hearing. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2006; 120:4019-30. [PMID: 17225428 DOI: 10.1121/1.2359235] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Simulations of cochlear implants have demonstrated that the deleterious effects of a frequency misalignment between analysis bands and characteristic frequencies at basally shifted simulated electrode locations are significantly reduced with training. However, a distortion of frequency-to-place mapping may also arise due to a region of dysfunctional neurons that creates a "hole" in the tonotopic representation. This study simulated a 10 mm hole in the mid-frequency region. Noise-band processors were created with six output bands (three apical and three basal to the hole). The spectral information that would have been represented in the hole was either dropped or reassigned to bands on either side. Such reassignment preserves information but warps the place code, which may in itself impair performance. Normally hearing subjects received three hours of training in two reassignment conditions. Speech recognition improved considerably with training. Scores were much lower in a baseline (untrained) condition where information from the hole region was dropped. A second group of subjects trained in this dropped condition did show some improvement; however, scores after training were significantly lower than in the reassignment conditions. These results are consistent with the view that speech processors should present the most informative frequency range irrespective of frequency misalignment.
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Affiliation(s)
- Matthew W Smith
- Department of Phonetics and Linguistics, UCL, Wolfson House, 4 Stephenson Way, London NW1 2HE, United Kingdom.
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Faulkner A, Rosen S, Norman C. The right information may matter more than frequency-place alignment: simulations of frequency-aligned and upward shifting cochlear implant processors for a shallow electrode array insertion. Ear Hear 2006; 27:139-52. [PMID: 16518142 DOI: 10.1097/01.aud.0000202357.40662.85] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE It has been claimed that speech recognition with a cochlear implant is dependent on the correct frequency alignment of analysis bands in the speech processor with characteristic frequencies (CFs) at electrode locations. However, the use of filters aligned in frequency to a relatively basal electrode array position leads to significant loss of lower frequency speech information. This study uses an acoustic simulation to compare two approaches to the matching of speech processor filters to an electrode array having a relatively shallow depth within the typical range, such that the most apical element is at a CF of 1851 Hz. Two noise-excited vocoder speech processors are compared, one with CF-matched filters, and one with filters matched to CFs at basilar membrane locations 6 mm more apical than electrode locations. DESIGN An extended crossover training design examined pre- and post-training performance in the identification of vowels and words in sentences for both processors. Subjects received about 3 hours of training with each processor in turn. RESULTS Training improved performance with both processors, but training effects were greater for the shifted processor. For a male talker, the shifted processor led to higher post-training scores than the frequency-aligned processor with both vowels and sentences. For a female talker, post-training vowel scores did not differ significantly between processors, whereas sentence scores were higher with the frequency-aligned processor. CONCLUSIONS Even for a shallow electrode insertion, we conclude that a speech processor should represent information from important frequency regions below 1 kHz and that the possible cost of frequency misalignment can be significantly reduced with listening experience.
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Affiliation(s)
- Andrew Faulkner
- Department of Phonetics and Linguistics, University College London, Wolfson House, London, United Kingdom.
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Affiliation(s)
- Colette M McKay
- School of Life and Health Sciences, Aston University, Birmingham B4 7ET, United Kingdom
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Dorman MF, Ketten D. Adaptation by a cochlear-implant patient to upward shifts in the frequency representation of speech. Ear Hear 2004; 24:457-60. [PMID: 14534415 DOI: 10.1097/01.aud.0000090438.20404.d9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The purpose of this project was to assess the degree to which a patient, after 1 wk of experience, could adapt to 3.2-mm and 6.8-mm basal shifts in the representation of speech. Only small deficits in performance were found after practice after the 3.2-mm shift. After practice after the 6.9-mm shift, scores on tests that emphasized amplitude envelope cues returned to baseline levels. Scores on vowel and sentence tests that emphasized frequency-based cues remained poor. Scores for "place," however, showed some recovery. Vowel recognition may be the limiting factor in recognizing basally shifted speech.
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Affiliation(s)
- Michael F Dorman
- Department of Speech and Hearing Science, Arizona State University, Tempe, AZ 85287-0102, USA.
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Fu QJ, Galvin JJ. The effects of short-term training for spectrally mismatched noise-band speech. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 113:1065-1072. [PMID: 12597199 DOI: 10.1121/1.1537708] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The present study examined the effects of short-term perceptual training on normal-hearing listeners' ability to adapt to spectrally altered speech patterns. Using noise-band vocoder processing, acoustic information was spectrally distorted by shifting speech information from one frequency region to another. Six subjects were tested with spectrally shifted sentences after five days of practice with upwardly shifted training sentences. Training with upwardly shifted sentences significantly improved recognition of upwardly shifted speech; recognition of downwardly shifted speech was nearly unchanged. Three subjects were later trained with downwardly shifted speech. Results showed that the mean improvement was comparable to that observed with the upwardly shifted training. In this retrain and retest condition, performance was largely unchanged for upwardly shifted sentence recognition, suggesting that these listeners had retained some of the improved speech perception resulting from the previous training. The results suggest that listeners are able to partially adapt to a spectral shift in acoustic speech patterns over the short-term, given sufficient training. However, the improvement was localized to where the spectral shift was trained, as no change in performance was observed for spectrally altered speech outside of the trained regions.
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Affiliation(s)
- Qian-Jie Fu
- Department of Auditory Implants and Perception, House Ear Institute, 2100 West Third Street, Los Angeles, California 90057, USA.
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Munson B, Donaldson GS, Allen SL, Collison EA, Nelson DA. Patterns of phoneme perception errors by listeners with cochlear implants as a function of overall speech perception ability. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2003; 113:925-935. [PMID: 12597186 DOI: 10.1121/1.1536630] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Many studies have noted great variability in speech perception ability among postlingually deafened adults with cochlear implants. This study examined phoneme misperceptions for 30 cochlear implant listeners using either the Nucleus-22 or Clarion version 1.2 device to examine whether listeners with better overall speech perception differed qualitatively from poorer listeners in their perception of vowel and consonant features. In the first analysis, simple regressions were used to predict the mean percent-correct scores for consonants and vowels for the better group of listeners from those of the poorer group. A strong relationship between the two groups was found for consonant identification, and a weak, nonsignificant relationship was found for vowel identification. In the second analysis, it was found that less information was transmitted for consonant and vowel features to the poorer listeners than to the better listeners; however, the pattern of information transmission was similar across groups. Taken together, results suggest that the performance difference between the two groups is primarily quantitative. The results underscore the importance of examining individuals' perception of individual phoneme features when attempting to relate speech perception to other predictor variables.
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Affiliation(s)
- Benjamin Munson
- Department of Communication Disorders, University of Minnesota, 115 Shevlin Hall, 164 Pillsbury Drive SE, Minneapolis, Minnesota 55455, USA
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