Factors that Influence Device Selection by Parents of Pediatric Cochlear Implant Candidates

The purpose of this study was to investigate factors/variables and the importance of those factors during cochlear implant (CI) device selection by parents of recent pediatric CI recipients in the United States. The researcher created an electronic survey and asked audiologists and hearing-related professionals at various hospitals and CI centers across the United States to distribute the survey link to the parents of any of their pediatric CI patients who received CI surgery within the past two years under the age of five years. The survey included both Likert-type and open-ended questions regarding the importance of various factors/variables to the parents during their child’s CI device selection. Results of the study found that the participants ranked reported reliability and speech perception performance of the respective manufacturer’s CI device as the most important factor. Individually, the parents of Cochlear, Ltd. recipients found recommendations from others and the popular brand of the company to be most important; based on a limited sample, parents of Advanced Bionics recipients found the CI device’s waterproof capabilities to be most important; and, also based on a limited sample, parents of MED-EL recipients found the reported speech perception performance to be most important

DEVELOPMENT AND EVALUATION OF ENVELOPE, SPECTRAL AND TIME ENHANCEMENT ALGORITHMS FOR AUDITORY NEUROPATHY

Auditory neuropathy (AN) is a hearing disorder that reduces the ability to detect temporal cues in speech, thus leading to deprived speech perception. Traditional amplification and frequency shifting techniques used in modern hearing aids are not suitable to assist individuals with AN due to the unique symptoms that result from the disorder. This study proposes a method for combining both speech envelope enhancement and time scaling to combine the proven benefits of each algorithm. In addition, spectral enhancement is cascaded with envelope and time enhancement to address the poor frequency discrimination in AN. The proposed speech enhancement strategy was evaluated using an AN simulator with normal hearing listeners under varying degrees of AN severity. The results showed a significant increase in word recognition scores for time scaling and envelope enhancement over envelope enhancement alone. Furthermore, the addition of spectral enhancement resulted in further increase in word recognition at profound AN severity

Dual electrode stimulation in cochlear implants : from concept to clinical application

With commonly used monopolar or __single electrode stimulation__ (SES) in cochlear implants the perceived pitch depends on the place in the cochlea of the stimulated contact. When two contacts are stimulated simultaneously, __dual electrode stimulation__(DES), intermediate pitches can be elicited. The place and precise pitch can be adjusted by varying the current ratio between these two contacts. In this thesis the mechanism of DES is investigated psychophysically, electrophysiologically and in a computational model of the cochlea. It was concluded that DES and SES are indistinguishable in terms of spread of excitation and sequential channel interaction, while with DES the pitch depends linearly on the current ratio. On adjacent contacts, DES turned out to be effective for the entire dynamic range without the need for any current correction to equalize loudness between pitches. DES is also feasible on non-adjacent contacts (__spanning__) up till 4.4 mm, but with increasing distance between the contacts, such a current correction becomes mandatory, while also the number of discriminable pitches decreases. Finally, spanning was implemented in a speech coding strategy and tested in a take-home trial, which demonstrated that even with two groups of three adjacent defective contacts, speech perception and sound quality were retained.Advanced Bionics (EU), ATOS medical, Beter Horen/Amplifon, Chipshoft BV, Daleco Pharma, GlaxoSmithKline, Med-El, Oticon, SpecsaversUBL - phd migration 201

High Fidelity Bioelectric Modelling of the Implanted Cochlea

Cochlear implants are medical devices that can restore sound perception in individuals with sensorineural hearing loss (SHL). Since their inception, improvements in performance have largely been driven by advances in signal processing, but progress has plateaued for almost a decade. This suggests that there is a bottleneck at the electrode-tissue interface, which is responsible for enacting the biophysical changes that govern neuronal recruitment. Understanding this interface is difficult because the cochlea is small, intricate, and difficult to access. As such, researchers have turned to modelling techniques to provide new insights. The state-of-the-art involves calculating the electric field using a volume conduction model of the implanted cochlea and coupling it with a neural excitation model to predict the response. However, many models are unable to predict patient outcomes consistently. This thesis aims to improve the reliability of these models by creating high fidelity reconstructions of the inner ear and critically assessing the validity of the underlying and hitherto untested assumptions. Regarding boundary conditions, the evidence suggests that the unmodelled monopolar return path should be accounted for, perhaps by applying a voltage offset at a boundary surface. Regarding vasculature, the models show that large modiolar vessels like the vein of the scala tympani have a strong local effect near the stimulating electrode. Finally, it appears that the oft-cited quasi-static assumption is not valid due to the high permittivity of neural tissue. It is hoped that the study improves the trustworthiness of all bioelectric models of the cochlea, either by validating the claims of existing models, or by prompting improvements in future work. Developing our understanding of the underlying physics will pave the way for advancing future electrode array designs as well as patient-specific simulations, ultimately improving the quality of life for those with SHL

Hearing Loss

Authored by 17 international researchers and research teams, the book provides up-to-date insights on topics in five different research areas related to normal hearing and deafness. Techniques for assessment of hearing and the appropriateness of the Mongolian gerbil as a model for age-dependent hearing loss in humans are presented. Parental attitudes to childhood deafness and role of early intervention for better treatment of hearing loss are also discussed. Comprehensive details are provided on the role of different environmental insults including injuries in causing deafness. Additionally, many genes involved in hearing loss are reviewed and the genetics of recessively inherited moderate to severe and progressive deafness is covered for the first time. The book also details established and evolving therapies for treatment of deafness