Cochleaimplantat (CI) är ett tekniskt hörselhjälpmedel som används av personer med grav hörselnedsättning eller dövhet. Ett CI ger barn med medfödd dövhet möjlighet att höra och utveckla talad kommunikation. CI ersätter inte normal hörsel och det finns stora individuella variationer i språk och talfärdighet hos personer med CI. Syftet med föreliggande studie var att studera kognitiva och språkliga förmågor hos barn med CI med fokus på läsförmåga. I studien deltog 57 barn i åldrarna 7;3-10;4 år. Sju av barnen hade CI. För att besvara frågeställningarna användes utvalda delar av SIPS (Sound Information Processing System), Fonemtest, TOWRE, Ortografiska val, Ortografisk inlärning, Woodcock och Blockmönster ur WISC III. Testresultatet analyserades på grupp- och individnivå och jämfördes med resultat från en kontrollgrupp med normalhörande barn. Barnen med CI presterade som grupp i nivå med normalhörande barn på majoriteten av testen. På de fonologiska testen presterade barnen med CI lägre än normalhörande men hade generellt en avkodningsförmåga i nivå med normalhörande barn. Barn med CI i årskurs 3 hade även en läsförståelse i nivå med normalhörande medan barnen med CI i årskurs 1-2 presterade signifikant lägre än normalhörande barn. Resultaten i studien indikerar att varken sen implantation, taluppfattningsnivå eller kommunikationssätt behöver leda till sämre läsförmåga. / A cochlear implant (CI) is a technical hearing device used by individuals with severe to profound hearing impairment. CI can provide children with congenital hearing impairment the abilities to hear and develop speech and language outcome. CI does not replace normal hearing and there are great individual variations in language and verbal skills in persons with CI. The aim of this study was to examine the cognitive and linguistic abilities in children with CI with focus on reading ability. In the present study 57 children between the ages of 7;3-10;4 participated.  Seven of the children had CI. SIPS (Sound Information Processing System), Phonological Output, TOWRE, Orthographic Choices, Orthographic Learning , Woodcock and Block Design Test from WISC III were selected to answer the question at issue. The results were analyzed both at a group and at an individual level and were compared with results from a group with normal hearing children. Children with CI performed as a group at the level of normal hearing children on the majority of the tests. The children with CI had lower performance levels than the normal hearing children in tasks of phonological skills but they generally had a decoding ability within the normal range for hearing children. Children with CI in grade 3 also demonstrated a reading comprehension within the normal range for hearing children whereas children with CI in grade 1-2 had lower performance level than normal hearing children. The results of the present study indicate that late implantation; neither speech perception nor means of communication have to result in poorer reading ability.

Children with Reading and Writing Difficulties and Their Language and Cognitive Abilities A Comparison with Children with a Cochlear Implant Abstract The aim of this study was to examine the cognitive abilities that are important for reading in children with reading disabilities, children with a cochlear implantation and typically developed children. 64 children aged 10-12 years participated in the study. To answer the question at issue we used the following tests: Block Design from WISC III, PPVT III, TOWRE, SL 40 and a few chosen tests out of the SIPS battery. On tests of the lexical access children with reading disabilities performed at the same level as hearing children, while the children with a cochlear implant performed significantly lower. Test of the phonological and complex working memory showed that children with reading disabilities performed significantly higher than children with a cochlear implant, but at the same time lower than typically developed children on the test of phonological working memory. Tests of reading ability showed that children with a cochlear implant performed at the same level as typically developed children, while children with reading disabilities showed lower results. The results indicate that the children with a cochlear implant can develop an adequate reading ability in spite of their phonological difficulties. Phonological skills do not seem to be the only factor influencing reading ability of the examined groups.

It has been hypothesized that increasing the number of active sites on a cochlear implant electrode array will enable the recipient to distinguish a higher number of pitch precepts, thus creating a more natural sound. While DSP processing strategies for cochlear implants have evolved significantly to address this, technology for the actual electrode array has remained relatively constant and limits the number of physical electrodes possible. Previous work introduced the concept of using Thin-Film Array (TFA) technology to allow for much higher site densities, although the original devices proved unreliable during surgical insertion tests. This work presents a new method of combining polyimide-based TFA's with supporting silicone insertion platforms to create assembled electrode arrays that are a more viable option for surgical insertion. The electrical and mechanical properties of these assemblies are investigated with physical deformation tests and finite element analysis in COMSOL to quantify how they will perform upon insertion into the cochlea, and the preliminary results of a surgical insertion study into human cadaveric temporal bones will be discussed.

In the present thesis, computer-assisted reading intervention with a phonics approach was examined in deaf and hard of hearing children (DHH) aged 5, 6 or 7 years old using cochlear implants, hearing aids or a combination of both. Children with normal hearing (NH), matched for non-verbal intelligence and age, served as a reference group. Deaf and hard of hearing children constitute a heterogenetic population regarding cognitive and academic achievement. Many of them do not reach age appropriate levels in language and reading ability during their school years, with negative consequences for later training facilities and job opportunities. Finding relevant intervention methods to promote early language learning and literacy development that are easy to implement is therefore of great importance. In this thesis three aspects of cognitive ability (phonological processing skills, lexical access and working memory capacity), and reading ability was examined at three points in time; baseline 1, pre intervention and post intervention. Additionally, computer-assisted training delivered by  means of the Internet in the children’s homes was explored in order to determine whether it would be a useful and efficient method for the DHH population. Overall, the results from the present thesis support the notion that offering a computer-assisted intervention program delivered at home, is an alternative way to support not only NH children with reading difficulties but also to support DHH children’s phonological development and decoding proficiency. / I denna avhandling undersöktes fonologisk lästräning vid datorn för döva och hörselskadade barn 5, 6 och 7 år gamla som använde cochleaimplantat, hörapparat eller en kombination av båda. Barn med normal hörsel som var matchade avseende icke-verbal intelligens och ålder utgjorde jämförelsegrupp. Döva och hörselskadade barn utgör en heterogen grupp avseende kognitiv förmåga och skolframgång. Många av dem når inte kraven för åldern avseende språk och läsförmåga under skoltiden vilket får negativa konsekvenser för senare utbildning och arbete. Att hitta relevanta interventionsmetoder för att främja tidig språkinlärning och läsutveckling som är lätta att genomföra, är därför av stor betydelse. I avhandlingen undersöktes tre aspekter av kognitiv förmåga (fonologisk bearbetningsförmåga, lexikal åtkomst och arbetsminneskapacitet) och läsförmåga vid tre tidpunkter; förtest 1, före intervention och efter intervention. Dessutom undersöktes om datorbaserad intervention som genomförs via Internet i hemmet, skulle vara en användbar och effektiv metod för döva och hörselskadade barn. Resultaten i stort visar att fonologisk lästräning vid datorn i barnens hem är en alternativ metod att stödja inte bara barn i risk att utveckla lässvårigheter, utan även döva och hörselskadade barns fonologi och avkodningsförmåga.

Effective cochlear implant fitting (or programming) is essential for providing good hearing outcomes, yet it is a subjective and error-prone task. The initial objective of this research was to automate the procedure using the auditory nerve electrically evoked compound action potential (the ECAP) and machine intelligence. The Nucleus?? cochlear implant measures the ECAP via its Neural Response Telemetry (NRT™) system. AutoNRT™, a commercial intelligent system that measures ECAP thresholds with the Nucleus Freedom™ implant, was firstly developed in this research. AutoNRT uses decision tree expert systems that automatically recognise ECAPs. The algorithm approaches threshold from lower stimulus levels, ensuring recipient safety during postoperative measurements. Clinical studies have demonstrated success on approximately 95% of electrodes, measured with the same efficacy as a human expert. NRT features other than ECAP threshold, such as the ECAP recovery function, could not be measured with similar success rates, precluding further automation and loudness prediction from data mining results. Despite this outcome, a better application of the ECAP threshold profile towards fitting was established. Since C-level profiles (the contour of maximum acceptable stimulus levels across the implant array) were observed to be flatter than T-level profiles (the contour of minimum audibility), a flattening of the ECAP threshold profile was adopted when applied as a fitting profile at higher stimulus levels. Clinical benefits of this profile scaling technique were demonstrated in a 42 subject study. Data mining results also provided an insight into the ECAP recovery function and refractoriness. It is argued that the ECAP recovery function is heavily influenced by the size of the recruited neural population, with evidence gathered from a computational model of the cat auditory nerve and NRT measurements with 21 human subjects. Slower ECAP recovery, at equal loudness, is a consequence of greater neural recruitment leading to lower mean spike probabilities. This view can explain the counterintuitive association between slower ECAP recovery and greater temporal responsiveness to increasing stimulation rate. This thesis presents the first attempt at achieving completely automated cochlear implant fitting via machine intelligence; a future generation implant, capable of high fidelity auditory system measurements, may realise the ultimate objective.

INTRODUÇÃO: A identificação e preservação da audição residual em candidatos a implante coclear vêm assumindo maior importância clínica. A resposta auditiva de estado estável (RAEE) pode fornecer informação frequência-específica sobre o limiar auditivo em níveis de intensidade máximos de 120 dB NA, possibilitando a investigação da audição residual. Os objetivos deste estudo são avaliar a audição residual em candidatos a implante coclear, comparando os limiares eletrofisiológicos da RAEE com os limiares psicoacústicos da audiometria nas frequências de 500, 1 000, 2 000 e 4 000 Hz. MÉTODO: Foram avaliados 40 candidatos a implante coclear (80 orelhas) com perda auditiva neurossensorial severa a profunda bilateral. A audiometria foi realizada com o tom \"warble\" nas frequências de 500, 1 000, 2 000 e 4 000 Hz com intensidade máxima de estimulação de 120 dB NA. A RAEE foi obtida através da estimulação dicótica de uma frequência de tons contínuos sinusoidais modulados 100% em amplitude exponencial e 20% em frequência, nas frequências portadoras de 500, 1 000, 2 000 e 4 000 Hz, com estimulação máxima de 117, 120, 119 e 118 dB NA, respectivamente. RESULTADOS: Foram obtidos limiares mensuráveis em 62,5% de todas as frequências estudadas na audiometria tonal e em 63,1% na RAEE. A RAEE apresentou sensibilidade de 96% e especificidade de 91,6% na detecção da audição residual. As diferenças médias entre os limiares da audiometria tonal e da RAEE não apresentaram significância estatística em nenhuma das frequências. As correlações entre os limiares comportamentais e da RAEE foram significantes em todas as frequências avaliadas, sendo fortes em 500, 1 000 e 2 000 Hz e moderada em 4 000 Hz, com coeficiente de correlação de Pearson entre 0,65 e 0,81. Em 90% dos casos, os limiares da RAEE foram adquiridos nos limites de 10 dB dos limiares comportamentais. CONCLUSÕES: As correlações entre os limiares tonais e da RAEE foram significantes nas frequências de 500, 1 000, 2 000 e 4 000 Hz. A RAEE apresentou alta sensibilidade e especificidade na detecção da audição residual em candidatos a implante coclear, em comparação com a audiometria tonal / INTRODUCTION: Identification and preservation of residual hearing in cochlear implantation are becoming more important lately. Auditory steadystate response (ASSR) can provide frequency-specific information regarding the auditory thresholds at maximum intensity levels of 120 dB HL, allowing investigation of residual hearing. The study objectives are to assess residual hearing in cochlear implant candidates by comparing the electrophysiological thresholds obtained in ASSR with psychoacoustic thresholds of audiometry at 500, 1 000, 2 000 and 4 000 Hz. METHOD: Forty cochlear implant candidates (80 ears) with bilateral severe-to-profound sensorineural hearing loss were studied. Warble-tone audiometry was performed at the frequencies 500, 1 000, 2 000 e 4 000 Hz, with stimuli up to 120 dB HL. ASSR was obtained with dichotic single-frequency stimulation of sinusoidal continuous tones modulated in exponential amplitude of 100% and in frequency of 20%, at the carrier frequencies of 500, 1 000, 2 000 and 4 000 Hz at maximum stimulation levels of 117, 120, 119 and 118 dB HL, respectively. RESULTS: Thresholds were obtained in 62,5% of all frequencies evaluated in warbletone audiometry and in 63,1% in the ASSR. ASSR showed sensitivity of 96% and specificity of 91,6% in the detection of residual hearing. The mean difference between the thresholds of behavioral audiometry and ASSR were not statistically significant in any of the frequencies. Strong correlations between behavioral and ASSR thresholds were observed in 500, 1 000 and 2 000 Hz and moderate in 4 000 Hz, with Pearson correlation coefficient between 0,65 and 0,81. In 90% of the occasions, ASSR thresholds were within 10 dB of behavioral thresholds. CONCLUSIONS: The correlations between behavioral and ASSR thresholds were significant at 500, 1 000, 2 000 and 4 000 Hz. ASSR showed high sensitivity and specificity in the detection of residual hearing in cochlear implant candidates, compared to warble-tone audiometry

L’implant cochléaire (IC) est une prothèse auditive implantée dans l’oreille interne qui a pour fonction de restaurer le sens de l’audition aux personnes atteintes de surdité sévère à profonde lorsque les aides auditives classiques ne leur permettent plus une audition suffisante. Pour pouvoir transmettre les indices provenant des sons extérieurs, l’IC contourne une grande partie du système auditif défaillant et stimule directement les fibres du nerf auditif du patient. En pratique, les électrodes de l’implant émettent des trains d’impulsions électriques modulées en amplitude. Ces trains d’impulsions ont une fréquence de répétition (cadence) constante. Un problème limitant est que nous ne connaissons pas entièrement les effets physiologiques et perceptifs liés à l’augmentation de la cadence de stimulation. Le projet de recherche lié à la présente thèse s’inscrit dans l’optique d’améliorer le codage temporel des futurs ICs. Cette thèse a pour but de mieux comprendre l’influence de la cadence de la stimulation électrique sur la perception des sons avec, comme objectif fondamental, de caractériser les mécanismes physiologiques sollicités lors d’une stimulation électrique. La cadence de la stimulation affecte au moins trois dimensions perceptives distinctes qui sont la hauteur, la durée et la sonie. Les expériences s’intéressent à résoudre des problèmes précis concernant chacune de ces dimensions. Lorsque nous le pouvions, les expériences réalisées chez le sujet IC ont également été réalisées chez des sujets normo-entendants en utilisant des simulations acoustiques d’ICs. / Cochlear implants (CIs) are auditory prostheses directly inserted in the inner ear to partly restore the sense of audition to people suffering from severe to profound deafness. In order to convey environmental sounds, CIs bypass the peripheral auditory system and produce amplitude-modulated electrical pulses that stimulate auditory nerve fibres. In general, pulses are delivered with a constant frequency of occurrence (i.e. rate). Even if CI users reach good performances to understand speech, it roughly diminishes when they are placed more complex audiological environment.A potential problem is that stimulation rates are not the same among subjects while our knowledge concerning the physiological mechanisms provided by rate variations, is limited. This thesis aims to improve temporal coding of CIs by studying the perceptual influence of stimulation rate, and quantify the physiological mechanisms sought by an electrical stimulation. At least, stimulation rate acts on three perceptual dimensions which are pitch, sound duration and loudness. The present experiment solves specific problems concerning each dimension cited previously. In addition to electrical stimulations, acoustical simulations of a CI were conducted to compare normal hearing with hearing-impaired performances.

An alternating treatment design was used to systematically evaluate the communication response forms, picture exchange communication system (PECS) or sign language, selection for a child with pervasive developmental disorder-not otherwise specified, profound hearing loss, and cochlear implants. The child had a limited pool of high preference items and very few functional skills. Key factors for this child included a structured environment that created a verbal community and contingent access to high preference items. No preference in communication response form was observed. The child successfully used four response forms to communicate: gestures, PECS, sign language, and vocalization. The results are discussed in terms of decision making factors in the selection of response forms.

Les implants cochléaires permettent aux personnes atteintes de surdité profonde de percevoir des sons. La modélisation comportementale de la partie externe de l’implant a été réalisée avec le logiciel Matlab. L’étude du canal de transmission et sa modélisation utilisant des modèles électriques de tissus biologiques a été ensuite effectuée ainsi que l’étude du niveau de bruit introduit par le canal. Deux types de modulations différentes sont réalisés à l’émission chacune nécessitant un oscillateur. L’étude théorique et la création d’un nouveau modèle afin d’évaluer le bruit de phase ont été proposés. L’extraction du jitter à partir du bruit de phase et son impact sur la chaine de réception complète a été estimée. La compréhension précise et la modélisation des différentes parties de l’oreille humaine qui conduisent à la stimulation des terminaisons nerveuses sont décrites. Par la suite nous avons développé un nouveau modèle mécanique de l’organe de Corti et du déplacement des stéréociles, que nous avons validé à l’aide de données provenant d’expériences physiques. La modélisation mathématique de la synapse entre les cellules ciliées et les fibres nerveuses a été réalisée, afin d’obtenir le stimulus électrique relatif à un son perçu quelconque. De plus un nouveau modèle analogique décrivant la propagation de l’information nerveuse a été développé. En se basant sur la spectroscopie d’impédance électrochimique des tissus biologiques, nous avons créé un modèle électrique du fil d’électrodes inséré dans la cochlée. / Cochlear implants are used by severely deaf people for partial hearing sensation. Behavioral modeling of the external part of the cochlear implant was first performed using the software Matlab. Then the propagation channel was modeled using electrical analogy of the biological tissues. Noise extraction of the propagation channel was performed in order to obtain the specifications for the RF receiver. Two types of diverse modulations are performed in the transmitter each one requiring an oscillator. The theoretical study and the creation of a new model allowing phase noise estimation is also proposed in this document. Jitter estimation from phase noise was performed and significantly impacted the overall chain transmission, suggesting oscillators blocks optimization. The accurate heterogeneous modeling of the various part of the internal ear leading to auditory nerve excitation was developed. Then a new mechanical equivalent of the organ of Corti and stereocilia displacement was developed and confirmed by physical experiments. The synapse between the hair cells and nerve fibers was mathematically modeled, in order to obtain the electrical stimulus of the auditory nerve associated with a random sound stimulus. Furthermore a new analog model of the nerve fiber information propagation was realized in order to obtain a realistic electrical analogy with nerve fiber depolarization propagation. Based on impedance spectroscopy biological tissue characterization, we proposed a new electrical analogy of the system composed of the electrodes inserted inside the cochlea.

In this work is in details described anatomy and physiology of auditory tract, all its pathological changes included. The main part of this work concetrates on the issue of hearing disorders compensation when special emphasis comes to cochlear implants. This work characterizes every single functional part of cochlear implants from microphones to electrode array. The thesis works in details with speech processors of cochlear implants and with possibilities that provides codes strategies. In a practical part of this thesis is designed the scetch of block scheme of the cochlear implant using CIS and ACE strategy. As an outcome has been made the programme for processing acoustic signal that is based on mentioned block scheme.