Mapping procedures can produce non-centered auditory images in bilateral cochlear implantees.
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ABSTRACT:
SUBMITTER: Goupell MJ
PROVIDER: S-EPMC3562277 | biostudies-other | 2013 Feb
REPOSITORIES: biostudies-other
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Project description:Spatial hearing skills are essential for children as they grow, learn and play. These skills provide critical cues for determining the locations of sources in the environment, and enable segregation of important sounds, such as speech, from background maskers or interferers. Spatial hearing depends on availability of monaural cues and binaural cues. The latter result from integration of inputs arriving at the two ears from sounds that vary in location. The binaural system has exquisite mechanisms for capturing differences between the ears in both time of arrival and intensity. The major cues that are thus referred to as being vital for binaural hearing are: interaural differences in time (ITDs) and interaural differences in levels (ILDs). In children with normal hearing (NH), spatial hearing abilities are fairly well developed by age 4-5 years. In contrast, most children who are deaf and hear through cochlear implants (CIs) do not have an opportunity to experience normal, binaural acoustic hearing early in life. These children may function by having to utilize auditory cues that are degraded with regard to numerous stimulus features. In recent years there has been a notable increase in the number of children receiving bilateral CIs, and evidence suggests that while having two CIs helps them function better than when listening through a single CI, these children generally perform worse than their NH peers. This paper reviews some of the recent work on bilaterally implanted children. The focus is on measures of spatial hearing, including sound localization, release from masking for speech understanding in noise and binaural sensitivity using research processors. Data from behavioral and electrophysiological studies are included, with a focus on the recent work of the authors and their collaborators. The effects of auditory plasticity and deprivation on the emergence of binaural and spatial hearing are discussed along with evidence for reorganized processing from both behavioral and electrophysiological studies. The consequences of both unilateral and bilateral auditory deprivation during development suggest that the relevant set of issues is highly complex with regard to successes and the limitations experienced by children receiving bilateral cochlear implants. This article is part of a Special Issue entitled <Annual Reviews 2016>.
| S-EPMC5647834 | biostudies-literature
Project description:PurposeThis current study aimed to explore early prelingual auditory development (EPLAD) and early language development in Mandarin-speaking children who received simultaneous bilateral cochlear implants (BICI) during the first year of cochlear implantation and compare the performance of the children who received BICI with those received unilateral cochlear implant (UCI).Methods39 Mandarin-speaking children who received BICIs simultaneously and 36 children with UCIs were enrolled in this study. To access the EPLAD, the Infant-Toddler Meaningful Auditory Integration Scale (IT/MAIS) was conducted, and a subtest of the simplified short-form version of the Mandarin Communicative Development Inventory (SSF-MCDI) was used to evaluate the development of expressive and receptive vocabulary for the children at indicated time points after surgery.ResultsIn both the simultaneous BICI and UCI groups, we observed significantly increased scores of the SSF-MCDI and IT/MAIS 1 year after the surgery. There are indications of early advantages in children with BICI in IT/MAIS scores (at 1, 3, and 6 months after activation). For early development of language, a great difference between the expressive vocabulary scores and the receptive vocabulary scores was observed in both groups. We found there were not significant differences between the two groups on expressive or receptive vocabulary scores, the use of more differentiated measures might be required in future research. We further found that the development of the receptive or expressive vocabulary is dramatically correlated with the age at implantation and the total scores of IT/MAIS for children with simultaneous BICIs.ConclusionThese results may supplement the skills development of early language and auditory in Mandarin-native children with simultaneous CIs. It is obvious that children with normal hearing have mastery of receptive vocabulary before that of expressive vocabulary, which is the same as children with unilateral and bilateral CIs in this research. IT/MAIS total scores and age at CI were important factors for early language performance in children with simultaneous BICIs.
| S-EPMC9669896 | biostudies-literature
Project description:In normal-hearing listeners, localization of auditory speech involves stimulus processing in the postero-dorsal pathway of the auditory system. In quiet environments, bilateral cochlear implant (CI) users show high speech recognition performance, but localization of auditory speech is poor, especially when discriminating stimuli from the same hemifield. Whether this difficulty relates to the inability of the auditory system to translate binaural electrical cues into neural signals, or to a functional reorganization of auditory cortical pathways following long periods of binaural deprivation is unknown. In this electroencephalography study, we examined the processing of auditory syllables in postlingually deaf adults with bilateral CIs and in normal-hearing adults. Participants were instructed to either recognize ("recognition" task) or localize ("localization" task) the syllables. The analysis focused on event-related potentials and oscillatory brain responses. N1 amplitudes in CI users were larger in the localization compared with recognition task, suggesting an enhanced stimulus processing effort in the localization task. Linear beamforming of oscillatory activity in CI users revealed stronger suppression of beta-band activity after 200 ms in the postero-dorsal auditory pathway for the localization compared with the recognition task. In normal-hearing adults, effects for longer latency event-related potentials were found, but no effects were observed for N1 amplitudes or beta-band responses. Our study suggests that difficulties in speech localization in bilateral CI users are not reflected in a functional reorganization of cortical auditory pathways. New signal processing strategies of cochlear devices preserving unambiguous binaural cues may improve auditory localization performance in bilateral CI users.
| S-EPMC6868941 | biostudies-literature
Project description:Cochlear implantation has become the standard-of-care for adults and children with severe to profound hearing loss. There is growing evidence that qualitative as well as quantitative deficits in the auditory nerve may affect cochlear implant (CI) outcomes. Auditory neuropathy spectrum disorder (ANSD) is characterized by dysfunctional transmission of sound from the cochlea to the brain due to defective synaptic function or neural conduction. In this review, we examine the precise mechanisms of genetic lesions causing ANSD and the effect of these lesions on CI outcomes. Reviewed data show that individuals with lesions that primarily affect the cochlear sensory system and the synapse, which are bypassed by the CI, have optimal CI outcomes. Individuals with lesions that affect the auditory nerve show poor performance with CIs, likely because neural transmission of the electrical signal from the CI is affected. We put forth a nuanced molecular classification of ANSD that has implications for preoperative counseling for patients with this disorder prior to cochlear implantation. We propose that description of ANSD patients should be based on the molecular site of lesion typically derived from genetic evaluation (synaptopathy vs. neuropathy) as this has implications for expected CI outcomes. Improvements in our understanding of genetic site of lesions and their effects on CI function should lead to better CI outcomes, not just for individuals with auditory neuropathy, but all individuals with hearing loss.
| S-EPMC6703118 | biostudies-literature
Project description:BackgroundSensorineural hearing loss occurs as a result of damage to the hair cells in the cochlea, or to the auditory nerve. It negatively affects learning and development in children, and employment and economic attainment in adults. Current policy in Ontario is to provide unilateral cochlear implantation for patients with bilateral severe to profound sensorineural hearing loss. However, hearing with both ears as a result of bilateral cochlear implantation may offer added benefits.MethodsWe completed a health technology assessment, which included an evaluation of clinical benefits and harms, value for money, budget impact, and patient preferences related to bilateral cochlear implantation. We performed a systematic literature search for studies on bilateral cochlear implantation in adults and children from inception to March 2017. We conducted a cost-utility analysis with a lifetime horizon from a public payer perspective and analyzed the budget impact of publicly funding bilateral cochlear implantation in adults and children in Ontario for the next 5 years. Finally, we conducted interviews with adults who have sensorineural hearing loss and unilateral or bilateral cochlear implants, and with parents of children with bilateral cochlear implants.ResultsWe included 24 publications (10 in adults, 14 in children) in the clinical evidence review. Compared with unilateral cochlear implantation, bilateral cochlear implantation improved sound localization, speech perception in noise, and subjective benefits of hearing in adults and children with severe to profound sensorineural hearing loss (GRADE: moderate to high). Bilateral cochlear implantation also allowed for better language development and more vocalization in preverbal communication in children (GRADE: moderate). The safety profile was acceptable.Bilateral cochlear implantation was more expensive and more effective than unilateral cochlear implantation. The incremental cost-effectiveness ratio was $48,978/QALY in adults and between $27,427/QALY and $30,386/QALY in children. Cost-effectiveness was highly dependent on the quality-of-life values used. We estimated that the net budget impact of publicly funding bilateral cochlear implantation for adults in Ontario would be between $510,000 and $780,000 per year for the next 5 years.Patients described the social and emotional effects of hearing loss, and the benefits and challenges of using cochlear implants.ConclusionsBased on evidence of moderate to high quality, we found that bilateral cochlear implantation improved hearing in adults and children with severe to profound sensorineural hearing loss. Bilateral cochlear implantation was potentially cost-effective compared to unilateral cochlear implantation in adults and children. Patients with sensorineural hearing loss reported the positive effects of cochlear implants, and patients with unilateral cochlear implants generally expressed a desire for bilateral implants.
| S-EPMC6235073 | biostudies-literature
Project description:OBJECTIVES:Binaural pitch fusion is the fusion of stimuli that evoke different pitches between the ears into a single auditory image. Individuals who use hearing aids or bimodal cochlear implants (CIs) experience abnormally broad binaural pitch fusion, such that sounds differing in pitch by as much as 3-4 octaves are fused across ears, leading to spectral averaging and speech perception interference. The goal of this study was to determine if adult bilateral CI users also experience broad binaural pitch fusion. DESIGN:Stimuli were pulse trains delivered to individual electrodes. Fusion ranges were measured using simultaneous, dichotic presentation of reference and comparison stimuli in opposite ears, and varying the comparison stimulus to find the range that fused with the reference stimulus. RESULTS:Bilateral CI listeners had binaural pitch fusion ranges varying from 0 to 12?mm (average 6.1?±?3.9?mm), where 12?mm indicates fusion over all electrodes in the array. No significant correlations of fusion range were observed with any subject factors related to age, hearing loss history, or hearing device history, or with any electrode factors including interaural electrode pitch mismatch, pitch match bandwidth, or within-ear electrode discrimination abilities. CONCLUSIONS:Bilateral CI listeners have abnormally broad fusion, similar to hearing aid and bimodal CI listeners. This broad fusion may explain the variability of binaural benefits for speech perception in quiet and in noise in bilateral CI users.
| S-EPMC5821581 | biostudies-literature
Project description:Although bilateral cochlear implant users receive input to both ears, they nonetheless have relatively poor localization abilities in the horizontal plane. This is likely because of the two binaural cues, they have good sensitivity to interaural differences of level (inter-aural level differences, or ILDs), but not those of time (inter-aural time differences; ITDs). Here, localization performance is assessed in six bilateral cochlear implant patients when instantaneous ITDs are measured and converted to ILDs, a strategy that results in larger-than-typical ILDs. The added ILDs are corrective, in that they are derived from individual listener performance across both frequency and azimuth, so that they are small where a listener performs well, and increase as performance deviates from ideal. Results show significantly improved localization performance as a result of this strategy, with two of the six listeners achieving levels of performance typically observed in NH listeners.
| S-EPMC5774684 | biostudies-literature
Project description:In the case of hearing loss, cochlear implants (CI) allow for the restoration of hearing. Despite the advantages of CIs for speech perception, CI users still complain about their poor perception of their auditory environment. Aiming to assess non-verbal auditory perception in CI users, we developed five listening tests. These tests measure pitch change detection, pitch direction identification, pitch short-term memory, auditory stream segregation, and emotional prosody recognition, along with perceived intensity ratings. In order to test the potential benefit of visual cues for pitch processing, the three pitch tests included half of the trials with visual indications to perform the task. We tested 10 normal-hearing (NH) participants with material being presented as original and vocoded sounds, and 10 post-lingually deaf CI users. With the vocoded sounds, the NH participants had reduced scores for the detection of small pitch differences, and reduced emotion recognition and streaming abilities compared to the original sounds. Similarly, the CI users had deficits for small differences in the pitch change detection task and emotion recognition, as well as a decreased streaming capacity. Overall, this assessment allows for the rapid detection of specific patterns of non-verbal auditory perception deficits. The current findings also open new perspectives about how to enhance pitch perception capacities using visual cues.
| S-EPMC8152499 | biostudies-literature
Project description:Across bilateral cochlear implants, contralateral threshold shift has been investigated as a function of electrode difference between the masking and probe electrodes. For contralateral electric masking, maximum threshold elevations occurred when the position of the masker and probe electrode was approximately place-matched across ears. The amount of masking diminished with increasing masker-probe electrode separation. Place-dependent masking occurred in both sequentially implanted ears, and was not affected by the masker intensity or the time delay from the masker onset. When compared to previous contralateral masking results in normal hearing, the similarities between place-dependent central masking patterns suggest comparable mechanisms of overlapping excitation in the central auditory nervous system.
| S-EPMC3574098 | biostudies-other
Project description:Nearly 100,000 deaf patients worldwide have had their hearing restored by a cochlear implant (CI) fitted to one ear. However, although many patients understand speech well in quiet, even the most successful experience difficulty in noisy situations. In contrast, normal-hearing (NH) listeners achieve improved speech understanding in noise by processing the differences between the waveforms reaching the two ears. Here we show that a form of binaural processing can be achieved by patients fitted with an implant in each ear, leading to substantial improvements in signal detection in the presence of competing sounds. The stimulus in each ear consisted of a narrowband noise masker, to which a tonal signal was sometimes added; this mixture was half-wave rectified, lowpass-filtered, and then used to modulate a 1000-pps biphasic pulse train. All four CI users tested showed significantly better signal detection when the signal was presented out of phase at the two ears than when it was in phase. This advantage occurred even though subjects only received information about the slowly varying sound envelope to be presented, contrary to previous reports that waveform fine structure dominates binaural processing. If this advantage generalizes to multichannel situations, it would demonstrate that envelope-based CI speech-processing strategies may allow patients to exploit binaural unmasking in order to improve speech understanding in noise. Furthermore, because the tested patients had been deprived of binaural hearing for eight or more years, our results show that some sensitivity to time-varying interaural cues can persist over extended periods of binaural deprivation.
| S-EPMC2504627 | biostudies-other