Cochlear implants in young children

The cochlear implant is best characterized as a device that provides access to the sound environment. The device enables the hearing pathway to respond to environmental and speech sounds, providing informational cues from the surroundings and from others that may escape visual detection. As the developmental effects of a profound hearing loss are multiple, cochlear implants have been applied to ever younger children in an attempt to promote a more normal level of developmental learning through audition. In deafness, transducer elements of the inner ear fail to trigger auditory nerve afferent nerves in the presence of sound input. However, large reserves of afferent fibers exist even in the auditory nerve of a profoundly deaf patient. Furthermore, these nerve fibers retain the ability to respond to prosthetic activation. Through developmental learning in the early, formative years, auditory centers of the brain appear capable of processing information from the implant to provide speech comprehension and oral language development. Multichannel implants have replaced original single channel designs. multichannel devices enable larger percentages of recipients to recognize the spoken word without visual cues because they provide spectral information in addition to temporal and intensity cues. Testing under conditions of auditory (implant)-only input reveals significant open-set speech understanding capabilities in more than 75% of children after three years of device use. The benefit provided by implants may vary with a number of conditions including: hearing history, age of deafness onset, age at implantation, etiology of deafness, linguistic abilities, and the presence of a motivated system of support of oral language development. Patient variables should be given individual consideration in judging candidacy for a cochlear implant and in planning rehabilitative and education services after surgery and activation of the device.     

Language development in profoundly deaf children with cochlear implants

Although cochlear implants improve the ability of profoundly deaf children to understand speech, critics claim that the published literature does not document even a single case of a child who has developed a linguistic system based on input from an implant. Thus, it is of clinical and scientific importance to determine whether cochlear implants facilitate the development of English language skills. The English language skills of prelingually deaf children with cochlear implants were measured before and after implantation. We found that the rate of language development after implantation exceeded that expected from unimplanted deaf children ( p < .001) and was similar to that of children with normal hearing. Despite a large amount of individual variability, the best performers in the implanted group seem to be developing an oral linguistic system based largely on auditory input obtained from a cochlear implant.     

Cochlear Implantation,Enhancements, Transhumanism and Posthumanism: Some Human Questions

Biomedical engineering technologies such as brain–machine interfaces and neuroprosthetics are advancements which assist human beings in varied ways. There are exciting yet speculative visions of how the neurosciences and bioengineering may influence human nature. However, these could be preparing a possible pathway towards an enhanced and even posthuman future. This article seeks to investigate several ethical themes and wider questions of enhancement, transhumanism and posthumanism. Four themes of interest are: autonomy, identity, futures, and community. Three larger questions can be asked: will everyone be enhanced? Will we be “human” if we are not, one day, transhuman? Should we be enhanced or not? The article proceeds by concentrating on a widespread and sometimes controversial application: the cochlear implant, an auditory prosthesis implanted into Deaf patients. Cochlear implantation and its reception in both the deaf and hearing communities have a distinctive moral discourse, which can offer surprising insights. The paper begins with several points about the enhancement of human beings, transhumanism’s reach beyond the human, and posthuman aspirations. Next it focuses on cochlear implants on two sides. Firstly, a shorter consideration of what technologies may do to humans in a transhumanist world. Secondly, a deeper analysis of cochlear implantation’s unique socio-political movement, its ethical explanations and cultural experiences linked with pediatric cochlear implantation—and how those wary of being thrust towards posthumanism could marshal such ideas by analogy. As transhumanism approaches, the issues and questions merit continuing intense analysis.     

Word learning in deaf children with cochlear implants: effects of early auditory experience

Word-learning skills were tested in normal-hearing 12- to 40-month-olds and in deaf 22- to 40-month-olds 12 to 18 months after cochlear implantation. Using the Intermodal Preferential Looking Paradigm (IPLP), children were tested for their ability to learn two novel-word/novel-object pairings. Normal-hearing children demonstrated learning on this task at approximately 18 months of age and older. For deaf children, performance on this task was significantly correlated with early auditory experience: Children whose cochlear implants were switched on by 14 months of age or who had relatively more hearing before implantation demonstrated learning in this task, but later implanted profoundly deaf children did not. Performance on this task also correlated with later measures of vocabulary size. Taken together, these findings suggest that early auditory experience facilitates word learning and that the IPLP may be useful for identifying children who may be at high risk for poor vocabulary development.     

Effects of talker variability on speechreading

The effects of talker variability on visual speech perception were tested by having subjects speechread sentences from either single-talker or mixed-talker sentence lists. Results revealed that changes in talker from trial to trial decreased speechreading performance. To help determine whether this decrement was due to talker change--and not a change in superficial characteristics of the stimuli--Experiment 2 tested speechreading from visual stimuli whose images were tinted by a single color, or mixed colors. Results revealed that the mixed-color lists did not inhibit speechreading performance relative to the single-color lists. These results are analogous to findings in the auditory speech literature and suggest that, like auditory speech, visual speech operations include a resource-demanding component that is influenced by talker variability.     

Everyday speechreading: understanding seen speech in action

How does speechreading (lipreading) work at the cognitive and neurobiological level? In this review I summarise work over the last fifteen years that has used everyday speechreading in hearing participants to illuminate issues of cerebral localisation and cognitive function. The implications of this work for deepening our understanding of speechreading in a remedial context are highlighted.     

听障学生汉语唇读面部加工方式的差异：来自眼动的证据

为探讨高低唇读理解能力听障学生唇读面部加工方式的差异,研究采用视频—图片匹配范式并结合眼动技术,考察高低唇读能力组语前-语中-语后和整体面部加工方式。结果发现,虽然两组都表现出社会协调模式,但高唇读能力组社会协调分数更高,且眼部维持时间更长。表明高唇读能力者整体加工和眼部、口形并行加工能力强,支持凝视假说和社会协调模式;低唇读能力者整体加工效率低,更依赖口形,未能通过补偿策略获得良好的补偿效果。     

Implicit sequence learning in deaf children with cochlear implants

Deaf children with cochlear implants (CIs) represent an intriguing opportunity to study neurocognitive plasticity and reorganization when sound is introduced following a period of auditory deprivation early in development. Although it is common to consider deafness as affecting hearing alone, it may be the case that auditory deprivation leads to more global changes in neurocognitive function. In this paper, we investigate implicit sequence learning abilities in deaf children with CIs using a novel task that measured learning through improvement to immediate serial recall for statistically consistent visual sequences. The results demonstrated two key findings. First, the deaf children with CIs showed disturbances in their visual sequence learning abilities relative to the typically developing normal-hearing children. Second, sequence learning was significantly correlated with a standardized measure of language outcome in the CI children. These findings suggest that a period of auditory deprivation has secondary effects related to general sequencing deficits, and that disturbances in sequence learning may at least partially explain why some deaf children still struggle with language following cochlear implantation.     

Ethical Dimension of Paediatric Cochlear Implantation

In congenitally or prelingually deaf childrencochlear implantation is open to seriousethical challenge. The ethical dimension ofthis technology is closely related to both asocial standard of quality of life and to theuncertainty of the overall results of cochlearimplantation. Uncertainty with regards theacquisition of oral communicative skills.However, in the western world, available datasuggest that deafness is associated with thelowest educational level and the lowest familyincome. Notwithstanding the existence of aDeaf-World, deafness should be considered as ahandicap. Therefore, society should provide themeans for the fulfilment of a deaf child'sspecific needs.For the time being there is no definitiveanswer with regard the best way to rehabilitatea particular deaf child. Therefore,communitarian values may be acceptable. If thedeaf child parents' decide not to implant,their decision should be respected. Guardiansare entitled to determine which standard ofbest interest to use in a specificcircumstance. They are the proper judges ofwhat (re)habilitation process is best for theirdeaf child. However, most deaf children areborn to two hearing parents. Probably, theywill not be acculturated in the Deaf-World. Itfollows that cochlear implantation is awelcomed (re)habilitation technology.If auditory (re)habilitation will in the futureprovide the necessary communicative skills, inparticular oral language acquisition, customs,values and attitudes of the hearing worldshould be regarded as necessary to accomplish adeaf child's right to an open future. Ifcochlear implantation technology will provideall deaf children with the capacity to developacceptable oral communicative skills –whatever the hearing status of the family andthe cultural environment – then auditory(re)habilitation will be an ethical imperative.     

Synchrony,complexity and directiveness in mothers’ interactions with infants pre- and post-cochlear implantation

This study investigated effects of profound hearing loss on mother–infant interactions before and after cochlear implantation with a focus on maternal synchrony, complexity, and directiveness. Participants included two groups of mother–infant dyads: 9 dyads of mothers and infants with normal hearing; and 9 dyads of hearing mothers and infants with profound hearing loss. Dyads were observed at two time points: Time 1, scheduled to occur before cochlear implantation for infants with profound hearing loss (mean age = 13.6 months); and Time 2 (mean age = 23.3 months), scheduled to occur approximately six months after cochlear implantation. Hearing infants were age-matched to infants with hearing loss at both time points. Dependent variables included the proportion of maternal utterances that overlapped infant vocalizations, maternal mean length of utterance, infant word use, and combined maternal directives and prohibitions. Results showed mothers’ utterances overlapped the vocalizations of infants with hearing loss more often before cochlear implantation than after, mothers used less complex utterances with infants with cochlear implants compared to hearing peers (Time 2), and mothers of infants with profound hearing loss used frequent directives and prohibitions both before and after cochlear implantation. Together, mothers and infants adapted relatively quickly to infants’ access to cochlear implants, showing improved interactional synchrony, increased infant word use, and levels of maternal language complexity compatible with infants’ word use, all within seven months of cochlear implant activation.     

Phonological representation and speech understanding with cochlear implants in deafened adults

In the present study cognitive performance in 15 deafened adult cochlear implant candidates was examined and related to level of speech understanding after 12 months of experience with the implant. The implant group performed on par with normal hearing controls in all cognitive tasks used in the study with one exception: Performance was significantly lower in cognitive tasks where use of a phonological representation of sound is a key task-demand. Observations of the implanted individuals’ level of speech understanding indicate that only those individuals who, pre-operatively, were in possession of phonological representations comparable to that of normal hearing could follow and understand a speaker that was out of sight. The results are discussed with respect to (a) deterioration in the phonological representation of sounds as a function of absence of external auditory stimulation, and (b) the role of cognitive factors in predicting success in speech understanding with the implant.     

McGurk stimuli for the investigation of multisensory integration in cochlear implant users: The Oldenburg Audio Visual Speech Stimuli (OLAVS)

The concurrent presentation of different auditory and visual syllables may result in the perception of a third syllable, reflecting an illusory fusion of visual and auditory information. This well-known McGurk effect is frequently used for the study of audio-visual integration. Recently, it was shown that the McGurk effect is strongly stimulus-dependent, which complicates comparisons across perceivers and inferences across studies. To overcome this limitation, we developed the freely available Oldenburg audio-visual speech stimuli (OLAVS), consisting of 8 different talkers and 12 different syllable combinations. The quality of the OLAVS set was evaluated with 24 normal-hearing subjects. All 96 stimuli were characterized based on their stimulus disparity, which was obtained from a probabilistic model (cf. Magnotti & Beauchamp, 2015). Moreover, the McGurk effect was studied in eight adult cochlear implant (CI) users. By applying the individual, stimulus-independent parameters of the probabilistic model, the predicted effect of stronger audio-visual integration in CI users could be confirmed, demonstrating the validity of the new stimulus material.     

The integration of auditory and visual motion signals at threshold

To interpret our environment, we integrate information from all our senses. For moving objects, auditory and visual motion signals are correlated and provide information about the speed and the direction of the moving object. We investigated at what level the auditory and the visual modalities interact and whether the human brain integrates only motion signals that are ecologically valid. We found that the sensitivity for identifying motion was improved when motion signals were provided in both modalities. This improvement in sensitivity can be explained by probability summation. That is, auditory and visual stimuli are combined at a decision level, after the stimuli have been processed independently in the auditory and the visual pathways. Furthermore, this integration is direction blind and is not restricted to ecologically valid motion signals.     

Does face familiarity influence speechreadability?

The impact of face familiarity on the speechreadability of faces is examined. First we measured the baseline speechreading performance of participants, from unfamiliar faces. Next, participants were familiarized with the face and voice of either the same or a different speaker, or were asked to take part in a word puzzle instead. Speechreading performance was measured again, before participants completed a further period of familiarization (or puzzle completion) and a final speechreading performance task. Results showed that speechreading performance increased overall with practice but that performance increased significantly more as participants became increasingly familiar with the same speaker. Our findings demonstrate the importance of talker-specific variations or other instance-based characteristics and suggest that these are a useful source of information for speechreading.     

Does face familiarity influence speechreadability?

The impact of face familiarity on the speechreadability of faces is examined. First we measured the baseline speechreading performance of participants, from unfamiliar faces. Next, participants were familiarized with the face and voice of either the same or a different speaker, or were asked to take part in a word puzzle instead. Speechreading performance was measured again, before participants completed a further period of familiarization (or puzzle completion) and a final speechreading performance task. Results showed that speechreading performance increased overall with practice but that performance increased significantly more as participants became increasingly familiar with the same speaker. Our findings demonstrate the importance of talker-specific variations or other instance-based characteristics and suggest that these are a useful source of information for speechreading.     

Perspectives on multisensory experience and cognitive development in infants with cochlear implants

Infants learn about their environment through sensory exploration, acquiring knowledge that is important for cognitive development. However, little is known about the sensory exploration of infants with profound hearing loss before or after they receive cochlear implants. This paper reviews aspects of sensory perception and cognitive development in hearing infants, discusses the implications of delayed access to auditory information for multisensory perception and cognitive development in infants who use cochlear implants, and suggests several new directions for research addressing multisensory exploration and cognitive development in infants with cochlear implants.     

Speech timing and working memory in profoundly deaf children after cochlear implantation

Thirty-seven profoundly deaf children between 8- and 9-years-old with cochlear implants and a comparison group of normal-hearing children were studied to measure speaking rates, digit spans, and speech timing during digit span recall. The deaf children displayed longer sentence durations and pauses during recall and shorter digit spans compared to the normal-hearing children. Articulation rates, measured from sentence durations, were strongly correlated with immediate memory span in both normal-hearing and deaf children, indicating that both slower subvocal rehearsal and scanning processes may be factors that contribute to the deaf children's shorter digit spans. These findings demonstrate that subvocal verbal rehearsal speed and memory scanning processes are not only dependent on chronological age as suggested in earlier research by. Instead, in this clinical population the absence of early auditory experience and phonological processing activities before implantation appears to produce measurable effects on the working memory processes that rely on verbal rehearsal and serial scanning of phonological information in short-term memory.     

Skilled speechreading: A single-case study

In a case study the cognitive characteristics of a skilled visual speechreader (SJ) was examined and compared to a control group. SJ is a 56 year old woman, skilled in visual speechreading. She differs from most of the 119 individuals in the control group, as she uses a particular speechreading strategy in which she attempts to repeat overtly each spoken word as soon as it has been uttered, and to summarize and fill in missing pieces of information whenever it is possible (e.g., during pauses) during the conversation.
SJ outperformed the control group on three types of tasks; a reading span task, performance in the asymptote level in the serial position curve, and verbal inference-making. SJ's results were discussed with respect to (a) how they relate to the general case (i.e., models based on group-data) and to (b) her speechreading strategy. From a clinical perspective it was suggested that it might be possible to practice the strategy as such, but any possible improvement is dependent on the individual's capability to process information in this way.     

The processing of fundamental frequency in a dichotic matching task

The temporal characteristics of auditory memory were investigated using a reaction time paradigm. The study attempted to determine whether or not there are functionally distinct left and right hemisphere components of auditory memory with different capacities for the retention of nonlinguistic information, such as fundamental frequency, over the course of several seconds. The results indicated that fundamental frequency information in auditory memory remains substantially unchanged over the course of 2 sec. No evidence was found for the existence of separate left and right hemisphere components of auditory memory with different temporal characteristics. The implications of this finding for the organization of auditory memory in the brain are discussed.