In identifying the importance of early identification of hearing loss in children, very little attention has been given to how advanced FM technology may improve outcomes. Distance, noise and reverberation remain considerable challenges for individuals using hearing aids, more so in really young children. The aim of this present research was to evaluate and explore the benefits of advanced integrated FM amplification technology with pre-school hearing aided children. The research was of a longitudinal prospective design, including both quantitative and qualitative analysis of FM technology use in pre-school hearing aided participants. All participants were provided with the latest hearing aid and integrated FM amplification technology suited to their hearing loss. An initial study was conducted to validate the 'AutoConnect' feature on the FM technology provided to participants. The manufacturers of the 'AutoConnect' purport the feature removes the need for verifying FM technology 'transparency'. The results indicated the feature did work with the hearing aid and FM combinations used in this study. Three further studies were conducted. The first of these evaluated FM device use via daily diaries, datalogging and questionnaires. Five of the seven families were able to establish regular FM use in a range of environments and settings. The environments where the FM was used most frequently were the home, car, nursery, shopping and outdoors. Listening evaluation measures with FM technology demonstrated the greatest improvements were in noise and at distance. Parents rated the FM technology highly, with all parents reporting 5 out of 5 for 'easy to operate'. Significant improvements in language development were noticed for the three children whose language development was identified as 'at risk' at the start of the study. The second of the three studies qualitatively explored the views and experiences of parents and carers on their use of FM technology. Eight weekly diaries, seven completed by parents and one completed by pre-school nursery staff of one of the participants, were collected throughout the study period. Seven semi structured interviews were conducted with parents at the end of study participation. Altogether eight cases were included for analysis with seven including both diaries and interviews and one case including diary only. Thematic content analysis sought to acknowledge parents and carers as the experts and place them in the centre of knowledge generation. Six main themes were identified: access to speech, listening, communication, wellbeing, engagement/ownership and practicalities of FM use. More detailed sub-themes were generated under the main six headings. Overall the analysis highlighted the potential benefits, barriers and challenges to pre-school use of FM technology. The final study used the language environment analysis (LENA) system to compare differences in language environment with and without FM use. The findings indicated the language environment of the children in this study was comparable to their hearing peers. The acoustic environment results suggested the largest portion of children's day was spent in environments where speech was at a distance or in background noise. The thesis concludes by discussing the findings and implications of this study and highlighting areas for future research. The current study provides a unique contribution to the existing literature and together with future research can be integral to the provision of FM technology as standard for pre-school hearing aided children.

Cochlear implants are a recognised treatment for severe and profound hearing losses, and can greatly improve speech discrimination in a quiet listening environment. However, poor specificity of neural excitation resulting from wide current spread within the cochlea leads to inadequate complex pitch perception, affecting speech discrimination in noisy environments and music perception. Tripolar is a stimulation mode with a greater degree of current focusing than the monopolar mode currently used in the clinic. The overall aim of the experiments in this thesis was to evaluate the potential of tripolar stimulation mode to improve complex pitch perception compared to monopolar stimulation mode in a group of Advanced Bionics cochlear implant listeners. First, the place specificity of tripolar and monopolar stimulation was compared using a psychophysical forward masking task with a dual-electrode masking stimulus to limit off-site listening. An overall improvement in the place specificity of tripolar compared to monopolar stimulation indicated that current focusing may provide more independent transmission of temporal information from different electrode places. This conclusion was unaffected by the degree of residual masking which, although measurable, was similar in both modes. Second, the effect of current focusing on delivery of independent temporal patterns was evaluated, specifically whether transmission of fine temporal information about interpulse intervals was improved using tripolar over monopolar stimulation. No advantage was found for current focusing in the delivery of temporal patterns on either a single electrode site, or across-electrodes. Third, the effect of mode on complex pitch perception was investigated by comparing a tripolar with a monopolar listening program. Results showed no improvement in pitch ranking ability from current focusing using sung vowel stimuli, and further suggested that a cue related to the centroid of excitation was providing a stronger cue to pitch than the temporal modulations available in both modes in this group. In conclusion, tripolar stimulation, on average, improved place specificity using forward masking, but not temporal cues to pitch using the methods chosen to evaluate this. Furthermore, current focusing did not improve the ability to rank sung vowels based on pitch over monopolar mode. Current focusing, therefore, was not found to enhance perception of complex harmonic pitch in this group. However, a degree of inter-participant variability in amount of benefit from current focusing observed in this series of experiments suggests that it may be useful for some cochlear implant listeners if a predictive measure of benefit were developed.

The main focus of the research presented within this thesis is, as the title suggests, binaural spatialization. Binaural technology and, especially, the binaural recording technique are not particu-larly recent. Nevertheless, the interest in this technology has lately become substantial due to the increase in the calculation power of personal computers, which started to allow the complete and accurate real-time simulation of three-dimensional sound-fields over headphones. The goals of this body of research have been determined in order to provide elements of novelty and of contribution to the state of the art in the field of binaural spatialization. A brief summary of these is found in the following list: • The development and implementation of a binaural spatialization technique with Distance Simulation, based on the individual simulation of the distance cues and Binaural Reverb, in turn based on the weighted mix between the signals convolved with the different HRIR and BRIR sets; • The development and implementation of a characterization process for modifying a BRIR set in order to simulate different environments with different characteristics in terms of frequency response and reverb time; • The creation of a real-time and offline binaural spatialization application, imple-menting the techniques cited in the previous points, and including a set of multichannel(and Ambisonics)-to-binaural conversion tools. • The performance of a perceptual evaluation stage to verify the effectiveness, realism, and quality of the techniques developed, and • The application and use of the developed tools within both scientific and artistic “case studies”. In the following chapters, sections, and subsections, the research performed between January 2006 and March 2010 will be described, outlining the different stages before, during, and after the development of the software platform, analysing the results of the perceptual evaluations and drawing conclusions that could, in the future, be considered the starting point for new and innovative research projects.

Σκοπός: Σκοπός της μελέτης ήταν η αξιολόγηση της δυνατότητας πρώιμης διάγνωσης της νόσου Ménière με τη χρήση ηχοκάλυψης χαμηλής συχνότητας. Υλικό και μέθοδος: Τριανταπέντε ασθενείς που έπασχαν από τη νόσο Ménière εξετάστηκαν επανειλημμένα κατά την πορεία της νόσου τους. Τα αποτελέσματα των ασθενών αυτών συγκρίθηκαν με αυτά που ελήφθησαν από 10 αυτιά με φυσιολογική ακοή και 40 αυτιά με βαρηκοΐα από θόρυβο. Οι μετρήσεις πραγματοποιήθηκαν με τη βοήθεια ειδικού εξοπλισμού ικανού να παράγει έναν ήχο χαμηλής συχνότητας σε συνδυασμό με ένα tone burst. Με τη βοήθεια των κατάλληλων μηχανημάτων ήταν δυνατή η ανεξάρτητη μεταβολή του πλάτους των δύο ηχητικών ερεθισμάτων, καθώς και της διαφοράς φάσης μεταξύ τους από 0 ως 360 μοίρες. Προσαρμόζοντας τις εντάσεις και τη διαφορά φάσης ο εξεταζόμενος μπορούσε να ακούσει δύο ήχους έναν χαμηλής συχνότητας ως ηχοκάλυψη και έναν υψηλής συχνότητας που ακουγόταν δυνατότερα από την ηχοκάλυψη. Η κύρια παράμετρος που μελετήθηκε ήταν το πλάτος διαμόρφωσης (modulation depth) που είναι η μέγιστη διαφορά μεταξύ του βέλτιστου και του χείριστου ουδού ακοής ενός εξεταζόμενου στο ακοόγραμμα φάσης και μετράται σε dB HL. Αποτελέσματα:Σε φυσιολογικά άτομα η αποτελεσματικότερη ηχοκάλυψη εντοπίστηκε στις 250° και η μικρότερη στις 360°. Λιγότερο αποτελεσματική ήταν η ηχοκάλυψη που παρατηρήθηκε στις 90°. Τα άτομα με φυσιολογική ακοή είχαν πλάτος διαμόρφωσης (modulation depth) μεταξύ 20 και 35 dB HL, οι ασθενείς με βαρηκοΐα αγωγιμότητας παρουσίασαν modulation depth περίπου 10 dB HL και στους ασθενείς με νόσο Ménière μετρήθηκε πλάτος modulation depth σχεδόν 0 dB. Συμπέρασμα: Ο εξοπλισμός και η μέθοδος που αναπτύξαμε πιθανόν να συμβάλλει στη διάγνωση και διαφορική διάγνωση της νόσου Ménière στα πρώιμα στάδια της και στις εξάρσεις που χαρακτηρίζουν την πορεία της. Ο εξοπλισμός που απαιτείται είναι απλός και προσιτός και μπορεί να βρεθεί σε οποιοδήποτε εργαστήριο ιατρικής φυσικής ή μηχανολογίας. Περισσότερες μελέτες είναι αναγκαίες προκειμένου να διερευνηθεί η πιθανή συμβολή της μελέτης του οπισθίου λαβυρίνθου με ηχοκάλυψη χαμηλής συχνότητας στην πρώιμη διάγνωση της νόσου Ménière. / OBJECTIVES: The evaluation of low frequency masking in early diagnosis of Ménière’s Disease (MD). PATIENTS AND METHODS: Thirty-five patients suffered from Ménière’s disease were examined. The results were compared with that of 10 normal hearing ears and 40 noise damaged ears. The examination of all of these individuals was made by the use of a special instrumentation capable to produce a low frequency sound signal superimposed with a tone burst. We were able to independently change the amplitudes of the two applied signals, as well as the phase lag between them from 0° to 360°. Adjusting the two amplitudes and the phase lag the examined individuals heard two sounds one as the masking tone and one high frequency tone superimposed to that of low frequency masking. RESULTS: In normal individuals the highest masking effect was evident at 250° and the lowest at 360°. A smaller masking effect was also evident at 90°. Normal hearing subjects had a modulation depth between 20 and 35 dB, while patients with noise damaged about 10 dB and patients with Ménière’s disease a modulation depth closing to 0 dB. The instrumentation and method presented in this article, shows a relative good clinical diagnostic accuracy as it is capable to diagnose the basilar membrane stiffness on an almost null modulation depth, and sensitivity near 70%. CONCLUSION: The developed instrumentation and method is possible to distinguish and diagnose the early stages of Ménière’s disease and also the acute recurrences. This may lead to a further study of the results of low frequency masking on the anterior labyrinth from research centers worldwide, in order to reinforce the diagnostic accuracy and strength of this newly developed diagnostic method.

Otitis media (OM) is characterised by inflammation of the middle ear and is a common cause of conductive hearing impairment that places a substantial social, medical and economic burden on healthcare systems globally. Despite the importance of the disease, the aetiology of chronic middle ear inflammatory disease remains poorly understood. The development and persistence of chronic OM is multi-factorial with a significant genetic component. A new mouse model of chronic OM, edison, was generated by N-ethyl-N-nitrosourea (ENU) mutagenesis and discovered in a recessive screen at MRC Harwell. Homozygous edison mice have craniofacial abnormalities, an emphysema-like lung phenotype and spontaneously develop a conductive hearing loss at 28 days as measured by ABR. Histological analysis shows the hearing loss is associated with the development of chronic OM in the middle ear, characterised by mucosal inflammation and highly cellular ear exudates. Similar to the Jeff and Junbo mutants, edison shows raised levels of Vegfa, Tnfα and Il-1β in middle ear fluids. A putative functional mutation was identified, resulting in a missense Leu972Pro change in a relatively unknown gene, Nischarin (Nisch). The identification of additional ENU-induced Nisch alleles, and subsequent characterisation, validated Nisch as the causative gene in edison. NISCH selectively binds ITGA5, which is thought to have a role in modulating VEGF signalling through SRC and FAK kinases. A significant genetic interaction between Nisch and Itga5 exists and impacts upon development of chronic OM. Mice heterozygous for Itga5-null and homozygous for edison alleles show a significantly increased penetrance and severity of chronic OM. Analysis of downstream pathways suggests that the edison allele is impacting upon both RAC1 and TGF-β/SMAD signalling. I also explored the potential use of the edison mouse as a model for bacterial challenge with the human otopathogen, NTHi. Similar to the Junbo infection model at MRC Harwell, the edison mouse was identified as a robust OM model for bacterial NTHi infection. The edison mouse highlights a new candidate gene for susceptibility to chronic OM and will provide further insight into the genetic pathways and pathogenic processes involved in chronic OM.

No description available.

The current behavioural dead region (DR) diagnosis methods such as psychophysical tuning curves and the threshold-equalising noise test require extensive subject co-operation. These present methods cannot be applied to infants. The work presented in the thesis aimed to develop a fast objective DR diagnosis method that could be applied to sleeping hearing-impaired infants. A novel fast objective electrophysiological method of recording response amplitude curves (RACs) which could enable objective DR diagnosis was developed.RACs were derived by recording auditory steady-state response amplitudes using modulated signals in the presence of narrow-band maskers. Two RAC methods were investigated. In the swept method, RACs were recorded in a single test run by recording the response amplitudes across the frequency range of a continuously swept-frequency narrow-band masker. In the fixed method, response amplitudes of eight separate test runs, each in the presence of differing fixed-frequency narrow-band maskers, were recorded.RACs were recorded in normally hearing adult subjects. The results showed that for normally hearing subjects in condition 1 (swept masker), the mean recorded RAC tip for a 2-kHz signal was 2250 Hz and the repeatability coefficient of two repeated recordings in each subject was 389 Hz; in condition 2 (fixed masker), the respective values were 2251 Hz and 342 Hz. These results indicated that the swept masking method is a viable and fast way to record RACs in normally hearing adults.RACs and psychophysical tuning curves (PTCs) were recorded in hearing-impaired adult subjects in order to asses the tip-frequency agreement between the tests. In some cases there were difficulties in using the required signal and masker levels due to maximum sound level limits. The RACs were poorly shaped and had poor repeatability. These findings indicate that the RAC method that was successfully applied to normally hearing subjects requires further development for use with the hearing impaired. The possible causes for the differences in the accuracy of the method between normally hearing and hearing-impaired subjects are discussed. The work presented in this thesis provides the basis upon which further research can be taken forward. It is envisaged that this work, together with further research, will lead to a clinically-effective objective DR diagnosis method.

Background to the study: Cochlear implants (CI) can help to suppress tinnitus and often make existing tinnitus more bearable. However, a number of patients still suffer from tinnitus afterwards. In some cases the implantation makes existing tinnitus worse, or tinnitus may occur as a result of cochlear implantation. Because of the inconclusive aetiology of tinnitus it is difficult to treat its effects. So far, one of the most popular treatments for tinnitus is the widely used Cognitive Behavioural Therapy (CBT), which aims to influence dysfunctional emotions, behaviours and cognitions though a goal-orientated, systematic procedure. CBT aims to minimize the side-effects of tinnitus and help to manage it in a more efficient way. CBT has been investigated in several studies and shows promising results in reducing the debilitating effect of tinnitus. CBT has not yet been used specifically for, or investigated in, relation to treating CI users suffering from tinnitus. Aims and outline of the study: Our research aimed to investigate CBT’s effectiveness for cochlear implant users. Using a randomized control trial, we investigated whether two-hour Tinnitus Workshops for the control group were as equally as effective as CBT for the research group. We also explored if either type of treatment for cochlear implant users needed any modifications to make them more suitable for this group of tinnitus sufferers. Using Open Questions, we investigated tinnitus in cochlear implant users. We analysed the Open Questions from both groups, creating a profile of a typical cochlear implant user who suffers from tinnitus, and we also explored whether both interventions (Tinnitus Workshop or CBT) were suitable for this kind of patient. Data was gathered, pre- and post-interventions, by questionnaires; these were Tinnitus Questionnaires (TQ), Visual Analogue Scale (VAS), Quality of Life Short Form 36 Health Survey (SF-36) and Hospital Anxiety and Depression Scale (HADS). Results: In the control group, we found no significant differences between the TQ scores pre- and post-intervention. VAS scores post-intervention were lower than pre-intervention, indicating some improvement in individual tinnitus perception; however, the difference was not significant. In the research group, we found small, but not significant, differences in both TQ pre- and post-intervention (z =1.83, p>.05) and in VAS (z=0.14, p>.05). No significant differences were found between the control and the research group pre- and post-intervention. Conclusions: The questionnaires used in this study, such as TQ or VAS, showed a decrease in general tinnitus distress, but a larger-sized sample group may be needed for greater statistical certainty. The results from the Open Questions showed that cochlear implant users were affected by tinnitus in a similar way to non-cochlear implant users. Overall, both interventions need further, small modifications and adjustments to their protocols in order to be more effective for this type of tinnitus sufferer.

L'audiométrie tonale liminaire est l'outil de référence pour évaluer le fonctionnement auditif, mais c'est un outil subjectif qui mesure des élévations de seuils témoignant de dégâts irréversibles sur le système auditif. La mesure des produits de distorsions acoustiques (PDAs), reflet du fonctionnement cochléaire, permet de dépister précocement des altérations de l'oreille interne causées par le bruit ou certains solvants ototoxiques. A partir d'un paradigme de mesure basé sur un enregistrement continu du PDA cubique (2f1-f2) et une stimulation controlatérale, nous avons pu expliquer, chez le rat, les effets pharmacologiques du toluène. Ce solvant aromatique agirait en particulier sur les centres nerveux impliqués dans le réflexe de protection acoustique de l'oreille moyenne. Devant les résultats obtenus chez l'animal, un prototype d'appareil adapté à l'homme a été mis au point, baptisé EchoScan. L'EchoScan a été testé sur 50 volontaires sains normo-entendant lors d'un premier protocole de recherche clinique pour vérifier la reproductibilité des mesures. Un second protocole a ensuite été conduit pour tester l'outil chez des salariés en entreprise, selon plusieurs conditions d'exposition : témoins non exposés, salariés exposés au bruit, exposés aux solvants, exposés au bruit et aux solvants. Les résultats des deux premières conditions sont présentés dans ce mémoire. Ils confirment la pertinence de la mesure du seuil du réflexe de l'oreille moyenne pour évaluer les effets de l'exposition au bruit. Les résultats des sujets exposés aux solvants évalueront la sensibilité de l'EchoScan dans la détection, voir la caractérisation des effets pharmacologiques de substances chimiques (inclusions en cours). Si l'avenir de l'EchoScan apparaît prometteur en médecine du travail, d'autres applications sont envisagées, comme l'étude des effets pharmacologiques des anesthésiques sur le réflexe de l'oreille moyenne / The pure-tone audiometry is a reference tool to assess auditory function but it is able to measure only threshold elevations showing irreversible damages. Measurement of distortion products oto-acoustic emissions (DPOAEs), reflecting the cochlear function, allows early detection of alterations in the inner ear caused by noise or some ototoxic solvents. From paradigm based on a continuous record of cubic DPOAEs (2f1-f2) and a contralateral stimulation triggering the middle-ear reflex, we could explain, in rats, the pharmacological effects of toluene. This aromatic solvent can act on the centers involved in the middle-ear acoustic protection reflex. With the results obtained in animals, a device adapted to humans has been developed, called EchoScan. The EchoScan was tested on 50 healthy volunteers with normal hearing in a first clinical research protocol to verify in particular the reproducibility of its measurements. A second research protocol was then conducted to test this tool among company employees, according to several exposure conditions: unexposed controls, workers exposed to noise, exposed to solvents, exposed to noise and solvents. The results of the first two conditions are presented in this thesis. They confirm the relevance of the measurement of the middle ear reflex threshold in assessing the effects of noise exposure. The results of subjects exposed to solvents will further evaluate the sensitivity of EchoScan in detection of the pharmacological effects, and even in the characterization of chemical substances exposure (in progress). In the future, EchoScan should be particularly promising in occupational medicine, but other applications are already considered, such as the study of pharmacological effects of anesthetics on the middle ear reflex

Cochlear dead regions (DRs) are areas in the cochlea where inner hair cells and/or neurones are functioning so poorly that a sound that causes peak basilar membrane motion in that region is more efficiently detected via off-frequency listening. The Threshold Equalising Noise (TEN) test is a clinical test procedure for detecting DRs. Psychophysical Tuning Curves (PTCs) can be used to identify the boundary frequency of the DR although the clinical importance of doing this has yet to be determined. Some studies have suggested that the reduction of amplification well inside the DR may be beneficial; however, other studies have been unable to replicate these findings in a more typical clinical population. Three studies were completed in order to:1. determine the prevalence of DRs in a clinical sample of the UK adult population,2. investigate repeatability, agreement and clinical feasibility of the TEN-test and fast PTCs in a clinical setting, and 3. determine the benefit of high-frequency amplification in ears with and without DRs, when listening to nonsense syllable speech material in quiet and babble. In the first study, 343 hearing-impaired adults were tested for DRs using the TEN-test. In total, 36% (95% confidence interval 31-41) of these adults had a DR in at least one ear, but frequently at 4 kHz only. Only 3% (1-5) of participants had a DR spanning more than three consecutive frequencies. These findings suggest that DRs usually only span 1 or 2 clinically-relevant frequencies. In the second study, the TEN-test was completed on 70 ears at frequencies between 0.5 and 4 kHz. Fast PTCs were measured on 20 ears at ≥ 2 frequencies. The TEN-test and fast PTCs were highly repeatable on retest (97% and 100%, respectively). There was 87% agreement between the two procedures in terms of the presence of off-frequency listening, with the TEN-test less likely to detect a DR than fast PTCs. Compared to the TEN-test, fast PTCs had a 10% lower ‘conclusive finding’ rate and the test duration was typically 40 minutes longer. Therefore, the TEN-test is more clinically acceptable, but it may underestimate the extent of a DR because of its inability to precisely identify the boundary frequency. In the third study, 18 ears with a high-frequency DR and 18 matched ears without a DR were tested. Vowel-Consonant-Vowel (VCV) stimuli were presented in quiet and babble when listening with an unfiltered and three low-pass filtered hearing aid settings. Best performance was obtained in the unfiltered condition; however the DR group performed significantly poorer than the controls in babble. There was no evidence to support reducing amplification in ears with a DR. However, participants with DRs may benefit from counseling about the limitations of listening in noise. In summary, DRs are relatively prevalent in hearing-impaired adults and can be diagnosed most efficiently in a clinical setting using the TEN-test. However, DRs are often restricted to a narrow frequency range and, in the typical adult clinical population, there is no evidence to support deviating from prescription targets.