Period Of Auditory Deprivation Research Articles

Early Deafened, Late Implanted Cochlear Implant Users Appreciate Music More Than and Identify Music as Well as Postlingual Users.

Introduction: Typical cochlear implant (CI) users, namely postlingually deafened and implanted, report to not enjoy listening to music, and find it difficult to perceive music. Another group of CI users, the early-deafened (during language acquisition) and late-implanted (after a long period of auditory deprivation; EDLI), report a higher music appreciation, but is this related to a better music perception?Materials and Methods: Sixteen EDLI and fifteen postlingually deafened (control group) CI users participated in the study. The inclusion criteria for EDLI were: severe or profound hearing loss onset before the age of 6 years, implantation after the age of 16 years, and CI experience more than 1 year. Subjectively, music perception and appreciation was evaluated using the Dutch Musical Background Questionnaire. Behaviorally, music perception was measured with melodic contour identification (MCI), using two instruments (piano and organ), each tested with and without a masking contour. Semitone distance between successive tones of the target varied from 1 to 3 semitones.Results: Subjectively, the EDLI group reported to appreciate music more than postlingually deafened CI users. Behaviorally, while clinical phoneme recognition test score on average was lower in the EDLI group, melodic contour identification did not significantly differ between the two groups. There was, however, an effect of instrument and masker for both groups; the piano was the best-recognized instrument, and for both instruments, the masker with non-overlapping pitch was best recognized.Discussion: EDLI group reported higher appreciation of music than postlingual control group, even though behaviorally measured music perception did not differ significantly between the two groups. Both surprising findings since EDLI CI users would be expected to have lower outcomes based on the early deafness onset, long duration of auditory deprivation, and on average lower clinical speech scores. Perhaps, the music perception difficulty comes from similar electric hearing limitations in both groups. The higher subjective appreciation in EDLI might be due to the lack of a musical memory, with no ability to compare music heard via the CI to acoustic music perception. Overall, our findings support a benefit from implantation for a positive music experience in EDLI CI users.

The effect of early auditory experience on the spatial listening skills of children with bilateral cochlear implants

ObjectivesBoth electrophysiological and behavioural studies suggest that auditory deprivation during the first months and years of life can impair listening skills. Electrophysiological studies indicate that 3½ years may be a critical age for the development of symmetrical cortical responses in children using bilateral cochlear implants. This study aimed to examine the effect of auditory experience during the first 3½ years of life on the behavioural spatial listening abilities of children using bilateral cochlear implants, with reference to normally hearing children. Data collected during research and routine clinical testing were pooled to compare the listening skills of children with bilateral cochlear implants and different periods of auditory deprivation. MethodsChildren aged 4–17 years with bilateral cochlear implants were classified into three groups. Children born profoundly deaf were in the congenital early bilateral group (received bilateral cochlear implants aged ≤3½ years, n=28) or congenital late bilateral group (received first implant aged ≤3½ years and second aged >3½ years, n=38). Children with some bilateral acoustic hearing until the age of 3½ years, who subsequently became profoundly deaf and received bilateral cochlear implants, were in the acquired/progressive group (n=16). There were 32 children in the normally hearing group. Children completed tests of sound-source localization and spatial release from masking (a measure of the ability to use both ears to understand speech in noise). ResultsThe acquired/progressive group localized more accurately than both groups of congenitally deaf children (p<0.05). All three groups of children with cochlear implants showed similar spatial release from masking. The normally hearing group localized more accurately than all groups with bilateral cochlear implants and displayed more spatial release from masking than the congenitally deaf groups on average (p<0.05). ConclusionChildren with bilateral cochlear implants and early experience of acoustic hearing showed more accurate localization skills, on average, than children born profoundly deaf.

Cross-modal reorganization in cochlear implant users: Auditory cortex contributes to visual face processing

There is converging evidence that the auditory cortex takes over visual functions during a period of auditory deprivation. A residual pattern of cross-modal take-over may prevent the auditory cortex to adapt to restored sensory input as delivered by a cochlear implant (CI) and limit speech intelligibility with a CI. The aim of the present study was to investigate whether visual face processing in CI users activates auditory cortex and whether this has adaptive or maladaptive consequences. High-density electroencephalogram data were recorded from CI users (n=21) and age-matched normal hearing controls (n=21) performing a face versus house discrimination task. Lip reading and face recognition abilities were measured as well as speech intelligibility. Evaluation of event-related potential (ERP) topographies revealed significant group differences over occipito-temporal scalp regions. Distributed source analysis identified significantly higher activation in the right auditory cortex for CI users compared to NH controls, confirming visual take-over. Lip reading skills were significantly enhanced in the CI group and appeared to be particularly better after a longer duration of deafness, while face recognition was not significantly different between groups. However, auditory cortex activation in CI users was positively related to face recognition abilities. Our results confirm a cross-modal reorganization for ecologically valid visual stimuli in CI users. Furthermore, they suggest that residual takeover, which can persist even after adaptation to a CI is not necessarily maladaptive.

The audiological journey and early outcomes of twelve infants with auditory neuropathy spectrum disorder from birth to two years of age

Objective: To describe the audiological journey of a group of infants with auditory neuropathy spectrum disorder (ANSD) following the fitting of hearing aids, and to investigate the potential benefits of including cortical auditory-evoked potentials (CAEPs) and a measure of functional auditory behaviour during early audiological management. Design: Results from chart revision of estimated hearing threshold, early behavioural testing, parental observation, and functional auditory behaviour assessments were described, and compared to visual reinforcement audiometry (VRA) thresholds obtained at a mean corrected age of 10 months (SD 3). The relationship with CAEPs and functional performance was examined. Study sample: The study included 12 infants diagnosed with ANSD and fitted with amplification. Results: The estimated 4FA at a mean corrected age of four months (SD5) was within ± 10 dB of VRA results in 75% of infants when unaided and aided behavioural observation audiometry (BOA), together with unaided and aided parental observations was combined. Infants with a greater proportion of CAEPs present had higher PEACH scores. Conclusions: Delaying amplification until VRA results were available would have led to a significant period of auditory deprivation for infants in this study group. None of the assessments could accurately determine hearing thresholds when used in isolation, however when used in combination clinicians were able to obtain sufficient information to fit hearing aids early, and identify infants requiring closer monitoring.

Bilateral cochlear implants in young children.

Cochlear implants (CIs) are provided to a growing number of people who are deaf. Single CIs offer opportunity for language acquisition, but there exist remaining challenges. In normal‐hearing individuals binaural hearing provides cues that are important for sound localization and speech understanding in noisy environments. Provision of bilateral CIs to many children occurs with the expectation that they will develop spatial hearing abilities. Outcomes in these children are mixed; while some are able to localize sound significantly better with bilateral CIs than with a single CI, other children demonstrate poor spatial hearing skills. Factors that seem to contribute to performance include amount of auditory deprivation prior to implantation and auditory experience following bilateral activation. Hardware/software limitations in implanted devices result in binaural cues being distorted or discarded. Studies using research processors show that these cues can be transmitted with fidelity to the patients, but that perceptual sensitivity to these cues may depend on the period of auditory deprivation that listeners have experienced. This talk will focus on progress and outcomes in children who are deaf and use bilateral CIs, with suggestions for future development that will depend on improved audio signal processing and signal delivery to the implantable devices.

Nonverbal Cognition in Deaf Children Following Cochlear Implantation: Motor Sequencing Disturbances Mediate Language Delays

We assessed profoundly deaf children with cochlear implants (CIs) (N = 24) and age-matched normal-hearing children (N = 31) on several nonverbal cognition measures: motor sequencing, tactile discrimination, response inhibition, visual-motor integration, and visual-spatial processing. The results revealed that the children with CIs showed disturbances solely on motor sequencing and that performance on this task was significantly correlated with scores on the Clinical Evaluation of Language Fundamentals, 4th Edition (CELF–4). These findings suggest that a period of auditory deprivation before cochlear implantation affects motor sequencing skills, which in turn may mediate the language delays displayed by some deaf children with CIs.

The influence of a sensitive period for auditory-visual integration in children with cochlear implants

Children who experience long periods of auditory deprivation are susceptible to large-scale reorganization of auditory cortical areas responsible for the perception of speech and language. One consequence of this reorganization is that integration of combined auditory and visual information may be altered after hearing is restored with a cochlear implant. Our goal was to investigate the effects of reorganization in a task that examines performance during multisensory integration. Reaction times to the detection of basic auditory (A), visual (V), and combined auditory-visual (AV) stimuli were examined in a group of normally hearing children, and in two groups of cochlear implanted children: (1) early implanted children in whom cortical auditory evoked potentials (CAEPs) fell within normal developmental limits, and (2) late implanted children in whom CAEPs were outside of normal developmental limits. Miller's test of the race model inequality was performed for each group in order to examine the effects of auditory deprivation on multisensory integration abilities after implantation. Results revealed a significant violation of the race model inequality in the normally hearing and early implanted children, but not in the group of late implanted children. These results suggest that coactivation to multi-modal sensory input cannot explain the decreased reaction times to multi-modal input in late implanted children. These results are discussed in regards to current models for coactivation to redundant sensory information.

Cochlear reimplantation in the same ear: Findings, peculiarities of the surgical technique and complications

IntroductionCochlear implants are, for many reasons, expirable electronic devices and may occasionally have to be replaced. The surgical cochlear reimplantation technique is not substantially different from the initial implantation but does have some peculiarities. These distinctive features are analysed in this paper not only from the point of view of surgical technique but also with respect to the complications involved and the functional auditory outcome obtained. ObjectivesAn accurate description of the surgical findings, peculiarities of the surgical technique and complications found during the process of cochlear reimplantation. An evaluation of the audiometric functional outcome of the reimplantation. Materials and methodA descriptive retrospective review of 34 reimplantations in the same ear, carried out at our department during the period between 1993 and 2008, in 27 patients in a tertiary hospital by the same team of senior surgeons. The cochlear implants replaced were 2 Ineraid® (Smith & Nephew Richards, TN), 23 Laura® (Philips Hearing Implants), 8 nucleus 24K® (Cochlear Corp., Englewood, CO) and 1 Clarion® (Advanced Bionics, Sylmar, CA). ResultsThe rate of reimplantation in the same ear was 18.5% per patient. The most frequent reason in our series was internal failure of the device (14 cases). Other causes were substitution for a technological update (7 cases), misplacement of electrodes (8 cases), necrosis/infection of the skin flap with exposure of the implant (3 cases) and external injuries (2 cases). The most important surgical findings were partial mastoidectomy reossification, absence of ossification in the posterior tympanostomy and the permeability of the basal turn of the cochlea when it housed the electrodes. Complete reintroduction of the electrodes was achieved in 25 patients and partial reintroduction in 2 patients. The rate of complications generated was similar in reimplantation and in virgin ear implantation, except for when the original implant was an Ineraid® device. ConclusionsThe surgical technique for reimplantation and multireimplantation has characteristic peculiarities at each step. However, in general terms, its complexity is similar to that of implantation in virgin ears and the rate of complications is also similar. The introduction of the new electrodes is simple and complete in the immense majority of cases, given that the cochlea remains permeable, as long as it houses the electrodes; otherwise it tends to become reossified. The functional auditory outcome of the new implant is in relation with its capacities. If these are equal to those of the initial implant, then the auditory outcome will be similar; if they are better, then so will the outcome be. One exception is ears with long periods of auditory deprivation.

Understanding speech in noise after correction of congenital unilateral aural atresia: Effects of age in the emergence of binaural squelch but not in use of head-shadow

Objective Unilateral hearing loss causes difficulty hearing in noise (the “cocktail party effect”) due to absence of redundancy, head-shadow, and binaural squelch. This study explores the emergence of the head-shadow and binaural squelch effects in children with unilateral congenital aural atresia undergoing surgery to correct their hearing deficit. Adding patients and data from a similar study previously published, we also evaluate covariates such as the age of the patient, surgical outcome, and complexity of the task that might predict the extent of binaural benefit – patients’ ability to “use” their new ear – when understanding speech in noise. Methods Patients with unilateral congenital aural atresia were tested for their ability to understand speech in noise before and again 1 month after surgery to repair their atresia. In a sound-attenuating booth participants faced a speaker that produced speech signals with noise 90 degrees to the side of the normal (non-atretic) ear and again to the side of the atretic ear. The Hearing in Noise Test (HINT for adults or HINT-C for children) was used to estimate the patients’ speech reception thresholds. The speech-in-noise test (SPIN) or the Pediatric Speech Intelligibility (PSI) Test was used in the previous study. Results There was consistent improvement, averaging 5 dB regardless of age, in the ability to take advantage of head-shadow in understanding speech with noise to the side of the non-atretic (normal) ear. There was, in contrast, a strong negative linear effect of age ( r 2 = .78, selecting patients over 8 years) in the emergence of binaural squelch to understand speech with noise to the side of the atretic ear. In patients over 8 years, this trend replicated over different studies and different tests. Children less than 8 years, however, showed less improvement in the HINT-C than in the PSI after surgery with noise toward their atretic ear (effect size = 3). No binaural result was correlated with degree of hearing improvement after surgery. Conclusions All patients are able to take advantage of a favorable signal-to-noise ratio in their newly opened ear; that is with noise toward the side of the normal ear (but this physical, bilateral, head-shadow effect need not involve true central binaural processing). With noise toward the atretic ear, the emergence of binaural squelch replicates between two studies for all but the youngest patients. Approximately 2 dB of binaural gain is lost for each decade that surgery is delayed, and zero (or poorer) binaural benefit is predicted after 38 years of age. Older adults do more poorly, possibly secondary to their long period of auditory deprivation. At the youngest ages, however, binaural results are different in open- and closed-set speech tests; the more complex hearing tasks may involve a greater cognitive load. Other cognitive abilities (late evoked potentials, grey matter in auditory cortex, and multitasking) show similar effects of age, peaking at the same late-teen/young-adult period. Longer follow-up is likely critical for the understanding of these data. Getting a new ear may be – like multitasking – challenging for the youngest and oldest subjects.

Cortical development, plasticity and re-organization in children with cochlear implants

A basic tenet of developmental neurobiology is that certain areas of the cortex will re-organize, if appropriate stimulation is withheld for long periods. Stimulation must be delivered to a sensory system within a narrow window of time (a sensitive period) if that system is to develop normally. In this article, we will describe age cut-offs for a sensitive period for central auditory development in children who receive cochlear implants. We will review de-coupling and re-organization of cortical areas, which are presumed to underlie the end of the sensitive period in congenitally deaf humans and cats. Finally, we present two clinical cases which demonstrate the use of the P1 cortical auditory evoked potential as a biomarker for central auditory system development and re-organization in congenitally deaf children fitted with cochlear implants. Learning outcomes: Readers of this article should be able to (i) describe the importance of the sensitive period as it relates to development of central auditory pathways in children with cochlear implants; (ii) discuss the hypothesis of de-coupling of primary from higher-order auditory cortex as it relates to the end of the sensitive period; (iii) discuss cross-modal re-organization which may occur after long periods of auditory deprivation; and (iv) understand the use of the P1 response as a biomarker for development of central auditory pathways.

Effects of auditory feedback deprivation length on the vowel ∕ε∕ produced by pediatric cochlear-implant users

Effects of auditory deprivation on speech production by ten cochlear-implanted children were investigated by turning off the implant for durations ranging from 0.3 to 5.0 s and measuring the formant frequencies (F1 and F2) of the vowel /epsilon/. In five of the ten talkers, F1 and/or F2 shifted when auditory feedback was eliminated. Without feedback, F2 frequency lowered consistently, suggesting vowel centralization. Phonetic transcription indicated that some of these acoustic changes led to perceptible shifts in phonetic quality. The results provide evidence that brief periods of auditory deprivation can produce perceptible changes in vowels produced by some cochlear-implanted children.

Central auditory development: Evidence from CAEP measurements in children fit with cochlear implants

In normal-hearing children the latency of the P1 component of the cortical evoked response to sound varies as a function of age and, thus, can be used as a biomarker for maturation of central auditory pathways. We assessed P1 latency in 245 congenitally deaf children fit with cochlear implants following various periods of auditory deprivation. If children experience less than 3.5 years of auditory deprivation before implantation, P1 latencies fall into the range of normal following 3–6 months of electrical stimulation. Children who experience greater than 7 years of deprivation, however, generally do not develop normal P1 latencies even after years of stimulation. Moreover, the waveforms for these patients can be markedly abnormal. Cortical reorganization stimulated by deprivation is likely to be a significant factor in both variation in the latency and morphology of the cortical evoked response to sound for children fit with a cochlear implant and variation in the development of oral speech and language function. Learning outcomes: The reader will be introduced to research using cortical evoked responses (CAEPs), positron emission tomography (PET) scans and in-depth recording from the auditory cortex of congenitally deaf cats that converges on the existence of a sensitive period for the development of central auditory pathways in children. The reader will also be provided with two case studies that illustrate the use of the P1 response as biomarker for development of central auditory pathways. Finally, suggestions for future research will be provided.

Effects of Auditory Deprivation on Cutaneous Sensitivity

Numerous experiments have shown that visual deprivation (darkness) produces cross-modal sensory enhancement effects. Only recently it has been demonstrated that auditory deprivation can produce similar effects. An experiment was conducted where subjects were exposed to a 1-wk. period of auditory deprivation (silence) with measures of their tactual fusion threshold being taken at daily intervals. The experimental subjects showed, relative to a control condition, a lowering of their threshold. The results are discussed in the context of the sensoristatic model, and the latter's capacity to account for these effects.