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Drakopoulos F, Vasilkov V, Osses Vecchi A, Wartenberg T, Verhulst S. Model-based hearing-enhancement strategies for cochlear synaptopathy pathologies. Hear Res 2022; 424:108569. [DOI: 10.1016/j.heares.2022.108569] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 07/07/2022] [Accepted: 07/12/2022] [Indexed: 11/04/2022]
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Gransier R, Wouters J. Neural auditory processing of parameterized speech envelopes. Hear Res 2021; 412:108374. [PMID: 34800800 DOI: 10.1016/j.heares.2021.108374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 10/01/2021] [Accepted: 10/13/2021] [Indexed: 10/19/2022]
Abstract
Speech perception depends highly on the neural processing of the speech envelope. Several auditory processing deficits are hypothesized to result in a reduction in fidelity of the neural representation of the speech envelope across the auditory pathway. Furthermore, this reduction in fidelity is associated with supra-threshold speech processing deficits. Investigating the mechanisms that affect the neural encoding of the speech envelope can be of great value to gain insight in the different mechanisms that account for this reduced neural representation, and to develop stimulation strategies for hearing prosthesis that aim to restore it. In this perspective, we discuss the importance of neural assessment of phase-locking to the speech envelope from an audiological view and introduce the Temporal Envelope Speech Tracking (TEMPEST) stimulus framework which enables the electrophysiological assessment of envelope processing across the auditory pathway in a systematic and standardized way. We postulate that this framework can be used to gain insight in the salience of speech-like temporal envelopes in the neural code and to evaluate the effectiveness of stimulation strategies that aim to restore temporal processing across the auditory pathway with auditory prostheses.
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Affiliation(s)
- Robin Gransier
- ExpORL, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium.
| | - Jan Wouters
- ExpORL, Department of Neurosciences, KU Leuven, 3000 Leuven, Belgium; Leuven Brain Institute, KU Leuven, 3000 Leuven, Belgium
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Neural Modulation Transmission Is a Marker for Speech Perception in Noise in Cochlear Implant Users. Ear Hear 2021; 41:591-602. [PMID: 31567565 DOI: 10.1097/aud.0000000000000783] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Cochlear implants (CIs) restore functional hearing in persons with a severe hearing impairment. Despite being one of the most successful bionic prosthesis, performance with CI (in particular speech understanding in noise) varies considerably across its users. The ability of the auditory pathway to encode temporal envelope modulations (TEMs) and the effect of degenerative processes associated with hearing loss on TEM encoding is assumed to be one of the reasons underlying the large intersubject differences in CI performance. The objective of the present study was to investigate how TEM encoding of the stimulated neural ensembles of human CI recipients is related to speech perception in noise (SPIN). DESIGN We used electroencephalography as a noninvasive electrophysiological measure to assess TEM encoding in the auditory pathway of CI users by means of the 40-Hz electrically evoked auditory steady state response (EASSR). Nine CI users with a wide range of SPIN outcome were included in the present study. TEM encoding was assessed for each stimulation electrode of each subject and new metrics; the CI neural modulation transmission difference (CIMTD) and the CI neural modulation transmission index (CIMTI) were developed to quantify the amount of variability in TEM encoding across the stimulated neural ensembles of the CI electrode array. RESULTS EASSR patterns varied across the CI electrode array and subjects. We found a strong correlation (r = 0.89, p = 0.001) between the SPIN outcomes and the variability in EASSR amplitudes across the array as assessed with CIMTD/CIMTI. CONCLUSIONS The results of the present study show that the 40-Hz EASSR can be used to objectively assess the neural encoding of TEMs in human CI recipients. Overall reduced or largely variable TEM encoding of the neural ensembles across the electrode array, as quantified with the CIMTD/CIMTI, is highly correlated with speech perception in noise outcome with a CI.
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Assessing temporal responsiveness of primary stimulated neurons in auditory brainstem and cochlear implant users. Hear Res 2021; 401:108163. [PMID: 33434815 PMCID: PMC7855898 DOI: 10.1016/j.heares.2020.108163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 11/19/2020] [Accepted: 12/27/2020] [Indexed: 11/24/2022]
Abstract
The reasons why clinical outcomes with auditory brainstem implants (ABIs) are generally poorer than with cochlear implants (CIs) are still somewhat elusive. Prior work has focused on differences in processing of spectral information due to possibly poorer tonotopic representation and higher channel interaction with ABIs than with CIs. In contrast, this study examines the hypothesis that a potential contributing reason for poor speech perception in ABI users may be the relative lack of temporal responsiveness of the primary neurons that are stimulated by the ABI. The cochlear nucleus, the site of ABI stimulation, consists of different neuron types, most of which have much more complex responses than the auditory nerve neurons stimulated by a CI. Temporal responsiveness of primary stimulated neurons was assessed in a group of ABI and CI users by measuring recovery of electrically evoked compound action potentials (ECAPs) from single-pulse forward masking. Slower ECAP recovery tended to be associated with poorer hearing outcomes in both groups. ABI subjects with the longest recovery time had no speech understanding or even no hearing sensation with their ABI device; speech perception for the one CI outlier with long ECAP recovery time was well below average. To the extent that ECAP recovery measures reveal temporal properties of the primary neurons that receive direct stimulation form neural prosthesis devices, they may provide a physiological underpinning for clinical outcomes of auditory implants. ECAP recovery measures may be used to determine which portions of the cochlear nucleus to stimulate, and possibly allow us to enhance the stimulation paradigms.
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Lamping W, Goehring T, Marozeau J, Carlyon RP. The effect of a coding strategy that removes temporally masked pulses on speech perception by cochlear implant users. Hear Res 2020; 391:107969. [PMID: 32320925 PMCID: PMC7116331 DOI: 10.1016/j.heares.2020.107969] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 03/26/2020] [Accepted: 04/05/2020] [Indexed: 01/11/2023]
Abstract
Speech recognition in noisy environments remains a challenge for cochlear implant (CI) recipients. Unwanted charge interactions between current pulses, both within and between electrode channels, are likely to impair performance. Here we investigate the effect of reducing the number of current pulses on speech perception. This was achieved by implementing a psychoacoustic temporal-masking model where current pulses in each channel were passed through a temporal integrator to identify and remove pulses that were less likely to be perceived by the recipient. The decision criterion of the temporal integrator was varied to control the percentage of pulses removed in each condition. In experiment 1, speech in quiet was processed with a standard Continuous Interleaved Sampling (CIS) strategy and with 25, 50 and 75% of pulses removed. In experiment 2, performance was measured for speech in noise with the CIS reference and with 50 and 75% of pulses removed. Speech intelligibility in quiet revealed no significant difference between reference and test conditions. For speech in noise, results showed a significant improvement of 2.4 dB when removing 50% of pulses and performance was not significantly different between the reference and when 75% of pulses were removed. Further, by reducing the overall amount of current pulses by 25, 50, and 75% but accounting for the increase in charge necessary to compensate for the decrease in loudness, estimated average power savings of 21.15, 40.95, and 63.45%, respectively, could be possible for this set of listeners. In conclusion, removing temporally masked pulses may improve speech perception in noise and result in substantial power savings.
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Affiliation(s)
- Wiebke Lamping
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark; Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, United Kingdom.
| | - Tobias Goehring
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, United Kingdom
| | - Jeremy Marozeau
- Hearing Systems Section, Department of Health Technology, Technical University of Denmark, DK-2800, Kgs. Lyngby, Denmark
| | - Robert P Carlyon
- Medical Research Council Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, United Kingdom
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DiNino M, O'Brien G, Bierer SM, Jahn KN, Arenberg JG. The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults. J Assoc Res Otolaryngol 2019; 20:291-303. [PMID: 30911952 PMCID: PMC6513958 DOI: 10.1007/s10162-019-00716-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 03/03/2019] [Indexed: 12/01/2022] Open
Abstract
Cochlear implant (CI) programming is similar for all CI users despite limited understanding of the electrode-neuron interface (ENI). The ENI refers to the ability of each CI electrode to effectively stimulate target auditory neurons and is influenced by electrode position, neural health, cochlear geometry, and bone and tissue growth in the cochlea. Hearing history likely affects these variables, suggesting that the efficacy of each channel of stimulation differs between children who were implanted at young ages and adults who lost hearing and received a CI later in life. This study examined whether ENI quality differed between early-implanted children and late-implanted adults. Auditory detection thresholds and most comfortable levels (MCLs) were obtained with monopolar and focused electrode configurations. Channel-to-channel variability and dynamic range were calculated for both types of stimulation. Electrical field imaging data were also acquired to estimate levels of intracochlear resistance. Children exhibited lower average auditory perception thresholds and MCLs compared with adults, particularly with focused stimulation. However, neither dynamic range nor channel-to-channel threshold variability differed between groups, suggesting that children’s range of perceptible current was shifted downward. Children also demonstrated increased intracochlear resistance levels relative to the adult group, possibly reflecting greater ossification or tissue growth after CI surgery. These results illustrate physical and perceptual differences related to the ENI of early-implanted children compared with late-implanted adults. Evidence from this study demonstrates a need for further investigation of the ENI in CI users with varying hearing histories.
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Affiliation(s)
- Mishaela DiNino
- Department of Psychology, Carnegie Mellon University, 5000 Forbes, Ave., Pittsburgh, PA, 15213, USA.
| | - Gabrielle O'Brien
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Steven M Bierer
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Kelly N Jahn
- Department of Speech and Hearing Sciences, University of Washington, 1417 NE 42nd St., Box 354875, Seattle, WA, 98105, USA
| | - Julie G Arenberg
- Department of Otolaryngology, Massachusetts Eye and Ear, Harvard Medical School, 243 Charles St., Boston, MA, 02114, USA
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Anis FN, Umat C, Ahmad K, Hamid BA. Patterns of recognition of Arabic consonants by non-native children with cochlear implants and normal hearing. Cochlear Implants Int 2018; 20:12-22. [PMID: 30293522 DOI: 10.1080/14670100.2018.1530420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
OBJECTIVE This study examined the patterns of recognition of Arabic consonants, via information transmission analysis for phonological features, in a group of Malay children with normal hearing (NH) and cochlear implants (CI). METHOD A total of 336 and 616 acoustic tokens were collected from six CI and 11 NH Malay children, respectively. The groups were matched for hearing age and duration of exposure to Arabic sounds. All the 28 Arabic consonants in the form of consonant-vowel /a/ were presented randomly twice via a loudspeaker at approximately 65 dB SPL. The participants were asked to repeat verbally the stimulus heard in each presentation. RESULTS Within the native Malay perceptual space, the two groups responded differently to the Arabic consonants. The dispersed uncategorized assimilation in the CI group was distinct in the confusion matrix (CM), as compared to the NH children. Consonants /ħ/, /tˁ/, /sˁ/ and /ʁ/ were difficult for the CI children, while the most accurate item was /k/ (84%). The CI group transmitted significantly reduced information, especially for place feature transmission, then the NH group (p < 0.001). Significant interactions between place-hearing status and manner-hearing status were also obtained, suggesting there were information transmission differences in the pattern of consonants recognition between the study groups. CONCLUSION CI and NH Malay children may be using different acoustic cues to recognize Arabic sounds, which contribute to the different assimilation categories' patterns within the Malay perceptual space.
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Affiliation(s)
- Farheen Naz Anis
- a Centre For Rehabilitation and Special Needs, Faculty of Health Sciences , Universiti Kebangsaan Malaysia , Jalan Raja Muda Abdul Aziz 50300 , Kuala Lumpur , Malaysia
| | - Cila Umat
- a Centre For Rehabilitation and Special Needs, Faculty of Health Sciences , Universiti Kebangsaan Malaysia , Jalan Raja Muda Abdul Aziz 50300 , Kuala Lumpur , Malaysia.,b Institute of Ear, Hearing & Speech, Universiti Kebangsaan Malaysia , Kuala Lumpur , Malaysia
| | - Kartini Ahmad
- a Centre For Rehabilitation and Special Needs, Faculty of Health Sciences , Universiti Kebangsaan Malaysia , Jalan Raja Muda Abdul Aziz 50300 , Kuala Lumpur , Malaysia
| | - Badrulzaman Abdul Hamid
- a Centre For Rehabilitation and Special Needs, Faculty of Health Sciences , Universiti Kebangsaan Malaysia , Jalan Raja Muda Abdul Aziz 50300 , Kuala Lumpur , Malaysia
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Brochier T, McKay C, McDermott H. Encoding speech in cochlear implants using simultaneous amplitude and rate modulation. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2018; 144:2042. [PMID: 30404505 DOI: 10.1121/1.5055989] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Accepted: 09/10/2018] [Indexed: 06/08/2023]
Abstract
To improve speech perception for cochlear implant (CI) users, it is essential to improve the transmission of temporal envelopes. The most common speech processors deliver temporal envelopes via the CI using fixed-rate amplitude modulated (AM) pulse trains. Psychophysical studies suggest that rate modulation (RM) and AM are perceived by a shared temporal integration mechanism, but the potential for them to constructively combine to encode temporal envelopes has yet to be explored. In this experiment, a speech processing strategy called amplitude and rate temporal modulation was developed to encode speech temporal envelopes with simultaneous AM and RM. The strategy was tested for perception of clean speech at 60 and 40 dBA, and 60 dBA speech in noise (+10 dB SNR). The amount of RM was varied and the amount of AM was held constant to determine whether the addition of RM could enhance the perception of temporal envelopes and improve speech understanding. At the lowest RM amount, speech scores were poorest for all speech conditions. For 60 dBA clean speech and speech in noise, speech scores were significantly better at the highest RM amounts, suggesting that RM combined with AM can be used to enhance perception of temporal envelopes.
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Affiliation(s)
- Tim Brochier
- Department of Medical Bionics, University of Melbourne, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Colette McKay
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
| | - Hugh McDermott
- The Bionics Institute, 384-388 Albert Street, East Melbourne, Victoria 3002, Australia
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