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Aljazeeri IA, Hagr A. Application of anatomy-based spacing of electrode contacts for achieving a uniform semitonal resolution: A novel concept in cochlear implant electrode design. Sci Rep 2024; 14:2645. [PMID: 38302541 PMCID: PMC10834526 DOI: 10.1038/s41598-024-53070-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 01/27/2024] [Indexed: 02/03/2024] Open
Abstract
Using anatomy-based fitting, we can determine the place-specific map with individualized center frequencies for each electrode contact that is a closer match to the natural pitch-place of the cochlea. The primary objective of this study is to evaluate the tonal presentation across the electrode array and to calculate the semitone difference between each adjacent pair of contacts according to their anatomy-based map. The secondary objective is to determine the distancing of the contacts that would result in an equal semitone difference with a uniform tonal presentation. A total of 167 ears were included in this retrospective study. The frequencies across the electrode arrays were found to be unequally presented. The semitonal condensations were higher in the apical inter-contact spaces compared to the basal inter-contact spaces, being 3.0-2.3 semitones/mm (Kruskal Wallis test, p < 0.000). The anatomy-based spacing of the electrode contacts was larger in the basal inter-contact spaces compared to the apical inter-contact spaces, ranging from 1.92 to 1.48 mm. In conclusion, the current electrode designs do not have uniform tonal representation throughout the electrode array. There is a more condensed tonal presentation in the apical electrodes than in the basal electrodes, resulting in a lower tonal resolution in the apical region.
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Affiliation(s)
- Isra Ali Aljazeeri
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, PO Box 245, 11411, Riyadh, Saudi Arabia.
- Otolaryngology and Ophthalmology Specialized Aljaber Hospital, Ministry of Health, Ahsa, Saudi Arabia.
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, PO Box 245, 11411, Riyadh, Saudi Arabia
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Creff G, Lambert C, Coudert P, Pean V, Laurent S, Godey B. Comparison of Tonotopic and Default Frequency Fitting for Speech Understanding in Noise in New Cochlear Implantees: A Prospective, Randomized, Double-Blind, Cross-Over Study. Ear Hear 2024; 45:35-52. [PMID: 37823850 DOI: 10.1097/aud.0000000000001423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
OBJECTIVES While cochlear implants (CIs) have provided benefits for speech recognition in quiet for subjects with severe-to-profound hearing loss, speech recognition in noise remains challenging. A body of evidence suggests that reducing frequency-to-place mismatch may positively affect speech perception. Thus, a fitting method based on a tonotopic map may improve speech perception results in quiet and noise. The aim of our study was to assess the impact of a tonotopic map on speech perception in noise and quiet in new CI users. DESIGN A prospective, randomized, double-blind, two-period cross-over study in 26 new CI users was performed over a 6-month period. New CI users older than 18 years with bilateral severe-to-profound sensorineural hearing loss or complete hearing loss for less than 5 years were selected in the University Hospital Centre of Rennes in France. An anatomical tonotopic map was created using postoperative flat-panel computed tomography and a reconstruction software based on the Greenwood function. Each participant was randomized to receive a conventional map followed by a tonotopic map or vice versa. Each setting was maintained for 6 weeks, at the end of which participants performed speech perception tasks. The primary outcome measure was speech recognition in noise. Participants were allocated to sequences by block randomization of size two with a ratio 1:1 (CONSORT Guidelines). Participants and those assessing the outcomes were blinded to the intervention. RESULTS Thirteen participants were randomized to each sequence. Two of the 26 participants recruited (one in each sequence) had to be excluded due to the COVID-19 pandemic. Twenty-four participants were analyzed. Speech recognition in noise was significantly better with the tonotopic fitting at all signal-to-noise ratio (SNR) levels tested [SNR = +9 dB, p = 0.002, mean effect (ME) = 12.1%, 95% confidence interval (95% CI) = 4.9 to 19.2, standardized effect size (SES) = 0.71; SNR = +6 dB, p < 0.001, ME = 16.3%, 95% CI = 9.8 to 22.7, SES = 1.07; SNR = +3 dB, p < 0.001 ME = 13.8%, 95% CI = 6.9 to 20.6, SES = 0.84; SNR = 0 dB, p = 0.003, ME = 10.8%, 95% CI = 4.1 to 17.6, SES = 0.68]. Neither period nor interaction effects were observed for any signal level. Speech recognition in quiet ( p = 0.66) and tonal audiometry ( p = 0.203) did not significantly differ between the two settings. 92% of the participants kept the tonotopy-based map after the study period. No correlation was found between speech-in-noise perception and age, duration of hearing deprivation, angular insertion depth, or position or width of the frequency filters allocated to the electrodes. CONCLUSION For new CI users, tonotopic fitting appears to be more efficient than the default frequency fitting because it allows for better speech recognition in noise without compromising understanding in quiet.
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Affiliation(s)
- Gwenaelle Creff
- Department of Otolaryngology-Head and Neck Surgery (HNS), University Hospital, Rennes, France
- MediCIS, LTSI (Image and Signal Processing Laboratory), INSERM, U1099, Rennes, France
| | - Cassandre Lambert
- Department of Otolaryngology-Head and Neck Surgery (HNS), University Hospital, Rennes, France
| | - Paul Coudert
- Department of Otolaryngology-Head and Neck Surgery (HNS), University Hospital, Rennes, France
| | | | | | - Benoit Godey
- Department of Otolaryngology-Head and Neck Surgery (HNS), University Hospital, Rennes, France
- MediCIS, LTSI (Image and Signal Processing Laboratory), INSERM, U1099, Rennes, France
- Hearing Aid Academy, Javene, France
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Gatto A, Tofanelli M, Costariol L, Rizzo S, Borsetto D, Gardenal N, Uderzo F, Boscolo-Rizzo P, Tirelli G. Otological Planning Software-OTOPLAN: A Narrative Literature Review. Audiol Res 2023; 13:791-801. [PMID: 37887851 PMCID: PMC10603892 DOI: 10.3390/audiolres13050070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 10/10/2023] [Accepted: 10/16/2023] [Indexed: 10/28/2023] Open
Abstract
The cochlear implant (CI) is a widely accepted option in patients with severe to profound hearing loss receiving limited benefit from traditional hearing aids. CI surgery uses a default setting for frequency allocation aiming to reproduce tonotopicity, thus mimicking the normal cochlea. One emerging instrument that may substantially help the surgeon before, during, and after the surgery is a surgical planning software product developed in collaboration by CASCINATION AG (Bern, Switzerland) and MED-EL (Innsbruck Austria). The aim of this narrative review is to present an overview of the main features of this otological planning software, called OTOPLAN®. The literature was searched on the PubMed and Web of Science databases. The search terms used were "OTOPLAN", "cochlear planning software" "three-dimensional imaging", "3D segmentation", and "cochlear implant" combined into different queries. This strategy yielded 52 publications, and a total of 31 studies were included. The review of the literature revealed that OTOPLAN is a useful tool for otologists and audiologists as it improves preoperative surgical planning both in adults and in children, guides the intraoperative procedure and allows postoperative evaluation of the CI.
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Affiliation(s)
- Annalisa Gatto
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Margherita Tofanelli
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Ludovica Costariol
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Serena Rizzo
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Daniele Borsetto
- Department of ENT, Addenbrookes Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - Nicoletta Gardenal
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Francesco Uderzo
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Paolo Boscolo-Rizzo
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
| | - Giancarlo Tirelli
- Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, 34149 Trieste, Italy; (A.G.); (N.G.); (G.T.)
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Saba JN, Ali H, Hansen JHL. The effects of estimation accuracy, estimation approach, and number of selected channels using formant-priority channel selection for an "n-of-m" sound processing strategy for cochlear implants. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 153:3100. [PMID: 37227411 PMCID: PMC10219683 DOI: 10.1121/10.0019416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 04/16/2023] [Accepted: 04/28/2023] [Indexed: 05/26/2023]
Abstract
Previously, selection of l channels was prioritized according to formant frequency locations in an l-of-n-of-m-based signal processing strategy to provide important voicing information independent of listening environments for cochlear implant (CI) users. In this study, ideal, or ground truth, formants were incorporated into the selection stage to determine the effect of accuracy on (1) subjective speech intelligibility, (2) objective channel selection patterns, and (3) objective stimulation patterns (current). An average +11% improvement (p < 0.05) was observed across six CI users in quiet, but not for noise or reverberation conditions. Analogous increases in channel selection and current for the upper range of F1 and a decrease across mid-frequencies with higher corresponding current, were both observed at the expense of noise-dominant channels. Objective channel selection patterns were analyzed a second time to determine the effects of estimation approach and number of selected channels (n). A significant effect of estimation approach was only observed in the noise and reverberation condition with minor differences in channel selection and significantly decreased stimulated current. Results suggest that estimation method, accuracy, and number of channels in the proposed strategy using ideal formants may improve intelligibility when corresponding stimulated current of formant channels are not masked by noise-dominant channels.
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Affiliation(s)
- Juliana N Saba
- University of Texas at Dallas, Center for Robust Speech Systems, Cochlear Implant Laboratory, 800 W. Campbell Rd, EC 33, Richardson, Texas 75080, USA
| | - Hussnain Ali
- University of Texas at Dallas, Center for Robust Speech Systems, Cochlear Implant Laboratory, 800 W. Campbell Rd, EC 33, Richardson, Texas 75080, USA
| | - John H L Hansen
- University of Texas at Dallas, Center for Robust Speech Systems, Cochlear Implant Laboratory, 800 W. Campbell Rd, EC 33, Richardson, Texas 75080, USA
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Dillon MT, Canfarotta MW, Buss E, Rooth MA, Richter ME, Overton AB, Roth NE, Dillon SM, Raymond JH, Young A, Pearson AC, Davis AG, Dedmon MM, Brown KD, O'Connell BP. Influence of Electric Frequency-to-Place Mismatches on the Early Speech Recognition Outcomes for Electric-Acoustic Stimulation Users. Am J Audiol 2023; 32:251-260. [PMID: 36800505 PMCID: PMC10166189 DOI: 10.1044/2022_aja-21-00254] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 05/21/2022] [Accepted: 11/28/2022] [Indexed: 02/19/2023] Open
Abstract
PURPOSE Cochlear implant (CI) recipients with hearing preservation experience significant improvements in speech recognition with electric-acoustic stimulation (EAS) as compared to with a CI alone, although outcomes across EAS users vary. The individual differences in performance may be due in part to default mapping procedures, which result in electric frequency-to-place mismatches for the majority of EAS users. This study assessed the influence of electric mismatches on the early speech recognition for EAS users. METHOD Twenty-one participants were randomized at EAS activation to listen exclusively with a default or place-based map. For both groups, the unaided thresholds determined the acoustic cutoff frequency (i.e., > 65 dB HL). For default maps, the electric filter frequencies were assigned to avoid spectral gaps in frequency information but created varying magnitudes of mismatches. For place-based maps, the electric filter frequencies were assigned to avoid frequency-to-place mismatches. Recognition of consonant-nucleus-consonant words and vowels was assessed at activation and 1, 3, and 6 months postactivation. RESULTS For participants with default maps, electric mismatch at 1500 Hz ranged from 2 to -12.0 semitones (Mdn = -5 semitones). Poorer performance was observed for those with larger magnitudes of electric mismatch. This effect was observed through 6 months of EAS listening experience. CONCLUSIONS The present sample of EAS users experienced better initial performance when electric mismatches were small or eliminated. These data suggest the utility of methods that reduce electric mismatches, such as place-based mapping procedures. Investigation is ongoing to determine whether these differences persist with long-term EAS use. SUPPLEMENTAL MATERIAL https://doi.org/10.23641/asha.22096523.
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Affiliation(s)
- Margaret T. Dillon
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
- Division of Speech and Hearing Sciences, Department of Allied Health Sciences, The University of North Carolina at Chapel Hill
| | - Michael W. Canfarotta
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
| | - Emily Buss
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
| | - Meredith A. Rooth
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
| | - Margaret E. Richter
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
- Division of Speech and Hearing Sciences, Department of Allied Health Sciences, The University of North Carolina at Chapel Hill
| | | | | | | | | | - Allison Young
- Department of Audiology, UNC Health, Chapel Hill, NC
| | | | - Amanda G. Davis
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
- Division of Speech and Hearing Sciences, Department of Allied Health Sciences, The University of North Carolina at Chapel Hill
| | - Matthew M. Dedmon
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
| | - Kevin D. Brown
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
| | - Brendan P. O'Connell
- Department of Otolaryngology/Head & Neck Surgery, School of Medicine, The University of North Carolina at Chapel Hill
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6
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Aljazeeri I, Hamed N, Abdelsamad Y, Sharif T, Al-Momani M, Hagr A. Anatomy-Based Frequency Allocation in Cochlear Implantation: The Importance of Cochlear Coverage. Laryngoscope 2021; 132:2224-2231. [PMID: 34967457 DOI: 10.1002/lary.30004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2021] [Revised: 12/09/2021] [Accepted: 12/17/2021] [Indexed: 11/08/2022]
Abstract
OBJECTIVES/HYPOTHESIS This study aimed to compare the predicted anatomy-based frequency allocation of cochlear implant electrodes with the default standard frequencies. STUDY DESIGN Retrospective study. METHODS A retrospective analysis was performed using computed tomography (CT) images of patients who received cochlear implants at a tertiary referral center. Patients were excluded if they had any congenital or acquired cochlear anatomical anomalies. The CT images of the patients were uploaded to the surgical planning software. Two independent reviewers allocated the anatomical parameters of the cochlea. The software then used these parameters to calculate the frequency allocation for each electrode according to the type of electrode and the length of the organ of Corti (OC) in each patient. These anatomy-based frequency allocations were compared with the default frequency settings. MAIN OUTCOME MEASURE Frequency-to-place mismatch in semitones. RESULTS A total of 169 implanted ears in 102 patients were included in this study. The readings of the two reviewers were homogenous, with a Cronbach's alpha of 0.98. The mean anatomy-based frequency allocation was 487.3 ± 202.9 Hz in electrode 1; 9,298.6 ± 490.6 Hz in electrode 12. The anatomy-based frequency allocations were found to be significantly higher than the frequencies of the default frequencies for each corresponding electrode (one-sample t-test, P < .001). The frequency-to-place mismatch was negatively correlated with cochlear coverage and positively correlated with the cochlear duct length (Pearson correlation > 0.65, P < .003). CONCLUSIONS The anatomy-based frequency allocation of each electrode is significantly different from the default frequency setting. This frequency-to-place mismatch was affected mainly by the cochlear coverage. LEVEL OF EVIDENCE 3 Laryngoscope, 2021.
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Affiliation(s)
- Isra Aljazeeri
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, Riyadh, Saudi Arabia.,Aljaber Ophthalmology and Otolaryngology Specialized Hospital, Ministry of Health, Ahsa, Saudi Arabia
| | - Nezar Hamed
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, Riyadh, Saudi Arabia
| | | | - Tahir Sharif
- Research Department, MED-EL GmbH, Riyadh, Saudi Arabia
| | - Murad Al-Momani
- ENT Department, College of Medicine, King Saud University, Riyadh, Saudi Arabia
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, Riyadh, Saudi Arabia
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7
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Eitutis ST, Jansen T, Borsetto D, Scoffings DJ, Tam YC, Panova T, Tysome JR, Donnelly NP, Axon PR, Bance ML. Cochlear Implantation in NF2 Patients Without Intracochlear Schwannoma Removal. Otol Neurotol 2021; 42:1014-1021. [PMID: 33710152 DOI: 10.1097/mao.0000000000003109] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine if cochlear implantation without removal of inner ear schwannomas (IES) is an effective treatment option for Neurofibromatosis 2 (NF2) patients. To determine how the presence of an intracochlear schwannoma might impact cochlear implant (CI) outcomes and programming parameters. STUDY DESIGN Retrospective chart review. SETTING Tertiary center for cochlear and auditory brainstem implantation. PATIENTS Of 10 NF2 patients with IES, 8 are reported with no previous tumor removal on the implanted ear. INTERVENTIONS Cochlear implant without tumor removal. MAIN OUTCOME MEASURES Performance outcomes with CI at least 1-year post intervention. Programming parameters, including impedances, for patients with IES. RESULTS All patients had full insertion of the electrode arrays with round window approaches. Performance outcomes ranged from 0 to 100% for Bamford-Kowal-Bench sentences. Impedance measurements for active electrodes for patients with IES were comparable to those measured in patients without vestibular schwannoma (VS). Only patients who had radiation treatment before receiving their implant had elevated threshold requirements for CI programming compared with CI recipients without VS. CONCLUSION Cochlear implantation without tumor removal is an effective option for treating NF2 patients with IES. The presence of an intracochlear tumor did not have an impact on CI performance or programming requirements compared with patients without VS; however, previous treatment with radiation may be related to elevated current requirements in the CI settings.
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Affiliation(s)
| | | | | | - Daniel J Scoffings
- Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge
| | | | | | | | | | | | - Manohar L Bance
- Department of Skull Based Surgery
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
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8
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Electrical Signal Modeling in Cochlear Implants. Study of Temperature and Humidity Effects. MICROMACHINES 2021; 12:mi12070785. [PMID: 34209421 PMCID: PMC8307363 DOI: 10.3390/mi12070785] [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] [Received: 04/06/2021] [Revised: 06/09/2021] [Accepted: 06/28/2021] [Indexed: 11/26/2022]
Abstract
The present paper discusses the climatic effects of humidity and temperature on cochlear implant functioning and the quality of the electrical sound signal. MATLAB Simulink simulations were prepared, offering insights into signal behavior under such climatic parameter changes. A simulation setup of the cochlear implant was developed, where a source type selection was used to change between a voice recording and a “chirp” sound. In addition, a DC blocking filter was applied to the input signal. A simulation code, with the application of the climatic influence via the air attenuation function, was developed. Thereby, the attenuation of temperature and humidity in the sound atmospheric circulation of the input signal, at T = 0 °C and RH = 0% and at T = 36 °C and RH = 40% was graphically represented. The results of the electrical pulse generator for each of the eight channels, with the IIR filter, Gaussian noise, temperature variation, humidity influence, and control of denoise block activity, were thus obtained.
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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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10
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Undurraga JA, Van Yper L, Bance M, McAlpine D, Vickers D. Neural encoding of spectro-temporal cues at slow and near speech-rate in cochlear implant users. Hear Res 2020; 403:108160. [PMID: 33461048 DOI: 10.1016/j.heares.2020.108160] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 10/22/2022]
Abstract
The ability to process rapid modulations in the spectro-temporal structure of sounds is critical for speech comprehension. For users of cochlear implants (CIs), spectral cues in speech are conveyed by differential stimulation of electrode contacts along the cochlea, and temporal cues in terms of the amplitude of stimulating electrical pulses, which track the amplitude-modulated (AM'ed) envelope of speech sounds. Whilst survival of inner-ear neurons and spread of electrical current are known factors that limit the representation of speech information in CI listeners, limitations in the neural representation of dynamic spectro-temporal cues common to speech are also likely to play a role. We assessed the ability of CI listeners to process spectro-temporal cues varying at rates typically present in human speech. Employing an auditory change complex (ACC) paradigm, and a slow (0.5Hz) alternating rate between stimulating electrodes, or different AM frequencies, to evoke a transient cortical ACC, we demonstrate that CI listeners-like normal-hearing listeners-are sensitive to transitions in the spectral- and temporal-domain. However, CI listeners showed impaired cortical responses when either spectral or temporal cues were alternated at faster, speech-like (6-7Hz), rates. Specifically, auditory change following responses-reliably obtained in normal-hearing listeners-were small or absent in CI users, indicating that cortical adaptation to alternating cues at speech-like rates is stronger under electrical stimulation. In CI listeners, temporal processing was also influenced by the polarity-behaviourally-and rate of presentation of electrical pulses-both neurally and behaviorally. Limitations in the ability to process dynamic spectro-temporal cues will likely impact speech comprehension in CI users.
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Affiliation(s)
- Jaime A Undurraga
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia.
| | - Lindsey Van Yper
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Manohar Bance
- Cambridge Hearing Group, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
| | - David McAlpine
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Deborah Vickers
- Cambridge Hearing Group, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
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11
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Goehring T, Arenberg JG, Carlyon RP. Using Spectral Blurring to Assess Effects of Channel Interaction on Speech-in-Noise Perception with Cochlear Implants. J Assoc Res Otolaryngol 2020; 21:353-371. [PMID: 32519088 PMCID: PMC7445227 DOI: 10.1007/s10162-020-00758-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/21/2020] [Indexed: 01/07/2023] Open
Abstract
Cochlear implant (CI) listeners struggle to understand speech in background noise. Interactions between electrode channels due to current spread increase the masking of speech by noise and lead to difficulties with speech perception. Strategies that reduce channel interaction therefore have the potential to improve speech-in-noise perception by CI listeners, but previous results have been mixed. We investigated the effects of channel interaction on speech-in-noise perception and its association with spectro-temporal acuity in a listening study with 12 experienced CI users. Instead of attempting to reduce channel interaction, we introduced spectral blurring to simulate some of the effects of channel interaction by adjusting the overlap between electrode channels at the input level of the analysis filters or at the output by using several simultaneously stimulated electrodes per channel. We measured speech reception thresholds in noise as a function of the amount of blurring applied to either all 15 electrode channels or to 5 evenly spaced channels. Performance remained roughly constant as the amount of blurring applied to all channels increased up to some knee point, above which it deteriorated. This knee point differed across listeners in a way that correlated with performance on a non-speech spectro-temporal task, and is proposed here as an individual measure of channel interaction. Surprisingly, even extreme amounts of blurring applied to 5 channels did not affect performance. The effects on speech perception in noise were similar for blurring at the input and at the output of the CI. The results are in line with the assumption that experienced CI users can make use of a limited number of effective channels of information and tolerate some deviations from their everyday settings when identifying speech in the presence of a masker. Furthermore, these findings may explain the mixed results by strategies that optimized or deactivated a small number of electrodes evenly distributed along the array by showing that blurring or deactivating one-third of the electrodes did not harm speech-in-noise performance.
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Affiliation(s)
- Tobias Goehring
- Cambridge Hearing Group, Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, UK.
| | - Julie G Arenberg
- Massachusetts Eye and Ear, Harvard Medical School, 243 Charles St, Boston, MA, 02114, USA
| | - Robert P Carlyon
- Cambridge Hearing Group, Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, UK
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Archer-Boyd AW, Southwell RV, Deeks JM, Turner RE, Carlyon RP. Development and validation of a spectro-temporal processing test for cochlear-implant listeners. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:2983. [PMID: 30522311 PMCID: PMC6805218 DOI: 10.1121/1.5079636] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 11/01/2018] [Indexed: 06/06/2023]
Abstract
Psychophysical tests of spectro-temporal resolution may aid the evaluation of methods for improving hearing by cochlear implant (CI) listeners. Here the STRIPES (Spectro-Temporal Ripple for Investigating Processor EffectivenesS) test is described and validated. Like speech, the test requires both spectral and temporal processing to perform well. Listeners discriminate between complexes of sine sweeps which increase or decrease in frequency; difficulty is controlled by changing the stimulus spectro-temporal density. Care was taken to minimize extraneous cues, forcing listeners to perform the task only on the direction of the sweeps. Vocoder simulations with normal hearing listeners showed that the STRIPES test was sensitive to the number of channels and temporal information fidelity. An evaluation with CI listeners compared a standard processing strategy with one having very wide filters, thereby spectrally blurring the stimulus. Psychometric functions were monotonic for both strategies and five of six participants performed better with the standard strategy. An adaptive procedure revealed significant differences, all in favour of the standard strategy, at the individual listener level for six of eight CI listeners. Subsequent measures validated a faster version of the test, and showed that STRIPES could be performed by recently implanted listeners having no experience of psychophysical testing.
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Affiliation(s)
- Alan W. Archer-Boyd
- MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - Rosy V. Southwell
- MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - John M. Deeks
- MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - Richard E. Turner
- MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - Robert P. Carlyon
- MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
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Selection of the appropriate cochlear electrode array using a specifically developed research software application. The Journal of Laryngology & Otology 2018; 132:544-549. [DOI: 10.1017/s0022215118000907] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractObjectiveTo evaluate the usefulness and reliability of a research software application for the estimation of an individual's cochlear duct length as a basis for electrode selection.MethodsIn this prospective cohort study, 21 consecutive patients (23 ears) implanted with a cochlear electrode were investigated. The study comprised 19 children (2 bilateral) and 2 adults.ResultsThe measured ‘A’ distances (the largest distance from the round window to the contralateral wall) corresponded to cochlear duct lengths of 28.5–36.4 mm. The mean cochlear duct length was 34.05 ± 1.72 mm (33.60 ± 2.27 mm in females and 34.35 ± 1.27 mm in males). Full insertion was achieved in all but two cases. No misplaced electrode array or electrode fold-over was detected. In all but three ears, the electrode was chosen based on the research software application's indication.ConclusionThe results show a good correlation between the pre-operatively predicted insertion depths using the software application and those post-operatively measured using X-ray. The insertion length predicted by the software was always longer than that measured via X-ray.
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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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Lai WK, Dillier N, Killian M. A Neural Excitability Based Coding Strategy for Cochlear Implants. ACTA ACUST UNITED AC 2018. [DOI: 10.4236/jbise.2018.117014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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van de Velde DJ, Schiller NO, van Heuven VJ, Levelt CC, van Ginkel J, Beers M, Briaire JJ, Frijns JHM. The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2017; 141:3349. [PMID: 28599540 PMCID: PMC5436976 DOI: 10.1121/1.4982198] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/15/2017] [Accepted: 04/11/2017] [Indexed: 06/07/2023]
Abstract
This study aimed to find the optimal filter slope for cochlear implant simulations (vocoding) by testing the effect of a wide range of slopes on the discrimination of emotional and linguistic (focus) prosody, with varying availability of F0 and duration cues. Forty normally hearing participants judged if (non-)vocoded sentences were pronounced with happy or sad emotion, or with adjectival or nominal focus. Sentences were recorded as natural stimuli and manipulated to contain only emotion- or focus-relevant segmental duration or F0 information or both, and then noise-vocoded with 5, 20, 80, 120, and 160 dB/octave filter slopes. Performance increased with steeper slopes, but only up to 120 dB/octave, with bigger effects for emotion than for focus perception. For emotion, results with both cues most closely resembled results with F0, while for focus results with both cues most closely resembled those with duration, showing emotion perception relies primarily on F0, and focus perception on duration. This suggests that filter slopes affect focus perception less than emotion perception because for emotion, F0 is both more informative and more affected. The performance increase until extreme filter slope values suggests that much performance improvement in prosody perception is still to be gained for CI users.
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Affiliation(s)
- Daan J van de Velde
- Leiden University Centre for Linguistics, Leiden University, Van Wijkplaats 3, 2311 BX, Leiden, the Netherlands
| | - Niels O Schiller
- Leiden University Centre for Linguistics, Leiden University, Van Wijkplaats 3, 2311 BX, Leiden, the Netherlands
| | - Vincent J van Heuven
- Department of Applied Linguistics, Pannon Egyetem, 10 Egyetem Utca, 8200 Veszprém, Hungary
| | - Claartje C Levelt
- Leiden University Centre for Linguistics, Leiden University, Van Wijkplaats 3, 2311 BX, Leiden, the Netherlands
| | - Joost van Ginkel
- Leiden University Centre for Child and Family Studies, Wassenaarseweg 52, 2333 AK, Leiden, the Netherlands
| | - Mieke Beers
- Leiden University Medical Center, Ears, Nose, and Throat Department, Postbus 9600, 2300 RC, Leiden, the Netherlands
| | - Jeroen J Briaire
- Leiden University Medical Center, Ears, Nose, and Throat Department, Postbus 9600, 2300 RC, Leiden, the Netherlands
| | - Johan H M Frijns
- Leiden University Medical Center, Ears, Nose, and Throat Department, Postbus 9600, 2300 RC, Leiden, the Netherlands
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Shannon RV. Auditory implant research at the House Ear Institute 1989-2013. Hear Res 2015; 322:57-66. [PMID: 25449009 PMCID: PMC4380593 DOI: 10.1016/j.heares.2014.11.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 11/04/2014] [Accepted: 11/07/2014] [Indexed: 11/29/2022]
Abstract
The House Ear Institute (HEI) had a long and distinguished history of auditory implant innovation and development. Early clinical innovations include being one of the first cochlear implant (CI) centers, being the first center to implant a child with a cochlear implant in the US, developing the auditory brainstem implant, and developing multiple surgical approaches and tools for Otology. This paper reviews the second stage of auditory implant research at House - in-depth basic research on perceptual capabilities and signal processing for both cochlear implants and auditory brainstem implants. Psychophysical studies characterized the loudness and temporal perceptual properties of electrical stimulation as a function of electrical parameters. Speech studies with the noise-band vocoder showed that only four bands of tonotopically arrayed information were sufficient for speech recognition, and that most implant users were receiving the equivalent of 8-10 bands of information. The noise-band vocoder allowed us to evaluate the effects of the manipulation of the number of bands, the alignment of the bands with the original tonotopic map, and distortions in the tonotopic mapping, including holes in the neural representation. Stimulation pulse rate was shown to have only a small effect on speech recognition. Electric fields were manipulated in position and sharpness, showing the potential benefit of improved tonotopic selectivity. Auditory training shows great promise for improving speech recognition for all patients. And the Auditory Brainstem Implant was developed and improved and its application expanded to new populations. Overall, the last 25 years of research at HEI helped increase the basic scientific understanding of electrical stimulation of hearing and contributed to the improved outcomes for patients with the CI and ABI devices. This article is part of a Special Issue entitled .
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Affiliation(s)
- Robert V Shannon
- Department of Otolaryngology, University of Southern California, Keck School of Medicine of USC, 806 W. Adams Blvd, Los Angeles, CA 90007-2505, USA.
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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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Prentiss S, Staecker H, Wolford B. Ipsilateral acoustic electric pitch matching: A case study of cochlear implantation in an up-sloping hearing loss with preserved hearing across multiple frequencies. Cochlear Implants Int 2014; 15:161-5. [DOI: 10.1179/1754762814y.0000000066] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Looi V, Winter P, Anderson I, Sucher C. A music quality rating test battery for cochlear implant users to compare the FSP and HDCIS strategies for music appreciation. Int J Audiol 2011; 50:503-18. [DOI: 10.3109/14992027.2011.562246] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Improving melody recognition in cochlear implant recipients through individualized frequency map fitting. Eur Arch Otorhinolaryngol 2010; 268:27-39. [DOI: 10.1007/s00405-010-1335-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Accepted: 07/02/2010] [Indexed: 10/19/2022]
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Cochlear implant patients' speech understanding in background noise: effect of mismatch between electrode assigned frequencies and perceived pitch. The Journal of Laryngology & Otology 2010; 124:828-34. [PMID: 20202276 DOI: 10.1017/s0022215110000320] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE To assess the electrode pitch function in a series of adults with postlingually implanted cochlear implants and with contralateral residual hearing, in order to investigate the correlation between the degree of frequency map mismatch and the subjects' speech understanding in quiet and noisy conditions. DESIGN Case series. SUBJECTS Seven postlingually deafened adults with cochlear implants, all with detectable contralateral residual hearing. Subjects' electrode pitch function was assessed by means of a pitch-matching test, in which they were asked to match an acoustic pitch (pure tones delivered to the non-implanted ear by an audiometer) to a perceived 'pitch' elicited by stimulation of the cochlear implant electrodes. A mismatch score was calculated for each subject. Speech recognition was tested using lists of sentences presented in quiet conditions and at +10, 0 and 5 dB HL signal-to-noise ratio levels (i.e. noise 10 dB HL lower than signal, noise as loud as signal and noise 5 dB HL higher than signal, respectively). Correlations were assessed using a linear regression model, with significance set at p < 0.05. RESULTS All patients presented some degree of mismatch between the acoustic frequencies assigned to their implant electrodes and the pitch elicited by stimulation of the same electrode, with high between-individual variability. A significant correlation (p < 0.005) was found between mismatch and speech recognition scores at +10 and 0 dB HL signal-to-noise ratio levels (r2 = 0.91 and 0.89, respectively). CONCLUSION The mismatch between frequencies allocated to electrodes and the pitch perceived on stimulation of the same electrodes could partially account for our subjects' difficulties with speech understanding in noisy conditions. We suggest that these subjects could benefit from mismatch correction, through a procedure allowing individualised reallocation of frequency bands to electrodes.
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Ming VL, Holt LL. Efficient coding in human auditory perception. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2009; 126:1312-20. [PMID: 19739745 PMCID: PMC2809690 DOI: 10.1121/1.3158939] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 03/14/2009] [Accepted: 06/03/2009] [Indexed: 05/28/2023]
Abstract
Natural sounds possess characteristic statistical regularities. Recent research suggests that mammalian auditory processing maximizes information about these regularities in its internal representation while minimizing encoding cost [Smith, E. C. and Lewicki, M. S. (2006). Nature (London) 439, 978-982]. Evidence for this "efficient coding hypothesis" comes largely from neurophysiology and theoretical modeling [Olshausen, B. A., and Field, D. (2004). Curr. Opin. Neurobiol. 14, 481-487; DeWeese, M., et al. (2003). J. Neurosci. 23, 7940-7949; Klein, D. J., et al. (2003). EURASIP J. Appl. Signal Process. 7, 659-667]. The present research provides behavioral evidence for efficient coding in human auditory perception using six-channel noise-vocoded speech, which drastically limits spectral information and degrades recognition accuracy. Two experiments compared recognition accuracy of vocoder speech created using theoretically-motivated, efficient coding filterbanks derived from the statistical regularities of speech against recognition using standard cochleotopic (logarithmic) or linear filterbanks. Recognition of the speech created using efficient encoding filterbanks was significantly more accurate than either of the other classes. These findings suggest potential applications to cochlear implant design.
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Affiliation(s)
- Vivienne L Ming
- Redwood Center for Theoretical Neuroscience, University of California at Berkeley, Berkeley, CA 94720, USA.
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Pretorius L, Hanekom J. Free field frequency discrimination abilities of cochlear implant users. Hear Res 2008; 244:77-84. [DOI: 10.1016/j.heares.2008.07.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2007] [Revised: 07/15/2008] [Accepted: 07/22/2008] [Indexed: 11/16/2022]
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Abstract
OBJECTIVES This study investigated the identification of familiar environmental sounds with varying spectral resolution to establish (1) the number of frequency channels needed to perceive a large heterogeneous set of familiar environmental sounds, (2) the role of cross-channel asynchrony in identification performance, and (3) the acoustic correlates of the spectral resolution required for identification. DESIGN In experiment 1, 60 normal-hearing listeners identified environmental sounds in a 60-alternative closed--set response task as a function of six spectral resolution conditions (i.e., 2, 4, 8, 16, 24, and 32 frequency channels) obtained with an envelope-vocoder. In experiment 2, identification accuracy for varying amounts of cross-channel asynchrony was determined for sounds with preserved and degraded fine spectral structure in 10 normal-hearing listeners. Experiment 3 examined identification performance of 72 listeners across six spectral resolution conditions as in experiment 1, but using three different signal processing methods designed to minimize cross-channel asynchrony across channels. Follow-up acoustic and discriminant analyses were carried out to identify parameters that can distinguish environmental sounds based on required spectral resolution. RESULTS Identification accuracy tended to improve with increasing spectral resolution reaching the maximum of 76%. However, in experiment 1, performance did not change significantly beyond eight channels, whereas identification accuracy of some sounds declined with increasing spectral resolution. In experiment 2, increases in cross-channel asynchrony for sounds with preserved fine spectra had a small, but significant negative effect on identification. However, minimizing the amount of asynchrony had no significant effect on the overall identification of spectrally degraded sounds in experiment 3. Acoustic analysis indicated several spectral and temporal measures that differed significantly between sounds that required eight or fewer channels and those that required 16 or more channels for 70% correct identification. Discriminant analysis revealed that the sounds could be classified into high- and low-required spectral resolution groups with 83% accuracy based on only two acoustic parameters: the number of bursts in the envelope and the standard deviation of spectral centroid velocity. CONCLUSIONS Increasing spectral resolution generally had a positive effect on identification of familiar environmental sounds. However, across conditions performance accuracy remained well-below that of control stimuli with preserved fine spectra, despite becoming asymptotic above eight channels. Cross-channel asynchrony introduced during vocoder processing, although detrimental for some sounds, was not a major factor that prevented further improvement in overall accuracy. A spectral resolution greater than 32 channels, along with additional fine spectral and temporal information may be required for identification of a number of environmental sounds. This study provides a preliminary basis for optimizing environmental sound perception by cochlear implant users by highlighting the role of several acoustic factors important for environmental sound identification.
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Bingabr M, Espinoza-Varas B, Loizou PC. Simulating the effect of spread of excitation in cochlear implants. Hear Res 2008; 241:73-9. [PMID: 18556160 DOI: 10.1016/j.heares.2008.04.012] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2007] [Revised: 04/26/2008] [Accepted: 04/28/2008] [Indexed: 10/22/2022]
Abstract
A model was developed to simulate acoustically the effects of excitation spread in cochlear implants (CI). Based on neurophysiologic data, the proposed model simulates the electrical-current decay rate associated with broad and narrow types of excitation, such as those produced by monopolar and bipolar electrode configurations. The effect of excitation spread on speech intelligibility was simulated in normal-hearing subjects by varying the slopes of the synthesis bands in the noise vocoder. Sentences and monosyllabic words processed via 4-16 channels of stimulation with varying degrees of excitation spread were presented to normal-hearing listeners for identification. Results showed significant interaction between spectral resolution (number of channels) and spread of excitation. The effect of narrowing the excitation spread was minimal when the spectral resolution was sufficiently good (>8 channels) but it was significant when the spectral resolution was poor (4 channels). A significant decrement in performance was observed for extremely narrow excitation spread. This outcome is partly consistent with behavioral data obtained with cochlear implant studies in that CI users tend to do as well or better with monopolar stimulation than with bipolar stimulation.
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Affiliation(s)
- Mohamed Bingabr
- Department of Engineering and Physics, University of Central Oklahoma, 100 North University Drive, Edmond, OK 73034, USA.
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Fallon JB, Irvine DRF, Shepherd RK. Cochlear implants and brain plasticity. Hear Res 2008; 238:110-7. [PMID: 17910997 PMCID: PMC2361156 DOI: 10.1016/j.heares.2007.08.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 08/15/2007] [Accepted: 08/15/2007] [Indexed: 01/13/2023]
Abstract
Cochlear implants have been implanted in over 110,000 deaf adults and children worldwide and provide these patients with important auditory cues necessary for auditory awareness and speech perception via electrical stimulation of the auditory nerve (AN). In 1942, Woolsey and Walzl presented the first report of cortical responses to localised electrical stimulation of different sectors of the AN in normal hearing cats, and established the cochleotopic organization of the projections to primary auditory cortex. Subsequently, individual cortical neurons in normal hearing animals have been shown to have well characterized input-output functions for electrical stimulation and decreasing response latencies with increasing stimulus strength. However, the central auditory system is not immutable, and has a remarkable capacity for plastic change, even into adulthood, as a result of changes in afferent input. This capacity for change is likely to contribute to the ongoing clinical improvements observed in speech perception for cochlear implant users. This review examines the evidence for changes of the response properties of neurons in, and consequently the functional organization of, the central auditory system produced by chronic, behaviourally relevant, electrical stimulation of the AN in profoundly deaf humans and animals.
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Affiliation(s)
- James B Fallon
- Bionic Ear Institute, 384-388 Albert Street, East Melbourne, VIC 3002, Australia.
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Stasiunas A, Verikas A, Miliauskas R, Stasiuniene N, Bacauskiene M. Physiologically inspired signal preprocessing for auditory prostheses: Insights from the electro-motility of the OHC. Med Eng Phys 2008; 30:171-81. [PMID: 17448719 DOI: 10.1016/j.medengphy.2007.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2006] [Revised: 11/30/2006] [Accepted: 03/02/2007] [Indexed: 10/23/2022]
Abstract
We designed a non-linear functional model of the outer hair cell (OHC) functioning in the filtering system of the cochlea and then isolated from it two second-order structures, one employing the mechanism of the somatic motility and the other the hair bundle motion of the OHC. The investigation of these circuits showed that the main mechanism increasing the sensitivity and frequency selectivity of the filtering system is the somatic motility. The mechanism of the active hair bundle motion appeared less suitable for realization of the band-pass filtering structures due to the dependence of the sensitivity, natural frequency and selectivity on the signal intensity. We combined three second-order filtering structures employing the mechanism of the somatic motility and the lateral inhibition to form a parallel-type filtering channel of the sixth order with the frequency characteristics of the Butterworth-type and Gaussian-type. The investigation of these channels showed that the Gaussian-type channel has the advantage over the Butterworth-type channel. It is more suitable for realization of a filter bank with common lateral circuits and has less distorted frequency characteristic in the nonlinear mode.
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Affiliation(s)
- Antanas Stasiunas
- Department of Applied Electronics, Kaunas University of Technology, LT-51368 Kaunas, Lithuania
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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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Abstract
PURPOSE OF REVIEW This review summarizes the history of cochlear implant signal processing and provides the rationale underlying current approaches. Present strategies are explained and recent research findings are summarized. It is suggested how these results may drive future advancements in signal processing. RECENT FINDINGS Substantial advances have been made in our understanding of the spectral and temporal cues necessary for cochlear implant recipients to perceive music, speech in noise, and interaural timing. It is clear that higher levels of both spectral and temporal resolution, as well as better loudness and pitch coding are necessary for higher levels of performance. These factors are highly interrelated, however, and are beneficial for differing aspects of hearing. Signal processing algorithms incorporating these findings are under active development and some are currently undergoing clinical investigation. SUMMARY Current implant devices, and those soon to be available, have substantial untapped potential to improve the auditory experience of their recipients. It is likely that in the near future, recent findings on pitch and loudness perception, as well as techniques to better emulate the normal functions of the cochlea will result in much higher levels of prosthetic hearing fidelity than are possible today. As the performance of these remarkable devices continues to improve, the population of hearing-impaired individuals who can benefit from implantation is likely to increase significantly.
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Affiliation(s)
- Jay T Rubinstein
- Departments of Otolaryngology and Bioengineering, The University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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31
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Abstract
This chapter describes the development of two implantable prosthetic neurostimulators which, in the last 20 years, have revolutionised the management of severe-to-profound sensorineural deafness. We have witnessed their rapid evolution from the realms of esoteric laboratory abstraction, with many critics and little perceived clinical use, to a routine treatment which is safe, effective and, indeed, cost effective. It is one of the great triumphs of biomedical and surgical collaboration, and is without any doubt the greatest ever advance in the treatment of deafness.
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Affiliation(s)
- James B. Fallon
- Bionic Ear Institute, 384-388 Albert Street, East Melbourne, VIC 3002, Australia
- Department of Otolaryngology, University of Melbourne, VIC 3002, Australia
| | - Dexter R. F. Irvine
- Bionic Ear Institute, 384-388 Albert Street, East Melbourne, VIC 3002, Australia
- School of Psychology, Psychiatry, and Psychological Medicine, Faculty of Medicine, Nursing, and Health Sciences, Monash University, VIC 3800, Australia
| | - Robert K. Shepherd
- Bionic Ear Institute, 384-388 Albert Street, East Melbourne, VIC 3002, Australia
- Department of Otolaryngology, University of Melbourne, VIC 3002, Australia
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