Improving Speech Perception Outcomes In Deaf Adults And Children Using Cochlear Implants
Funder
National Health and Medical Research Council
Funding Amount
$160,604.00
Summary
This project aims to further improve on speech understanding by deaf adults and children using the cochlear implant. In particular, we aim to individually modify the speech coding scheme on the basis of the basic hearing skills of the subject. In this manner, more speech information should be available and the users will likely gain more benefit from their cochlear implants. The speech processing strategy of the multiple-electrode cochlear implant, manufactured by the Australian biomedical compa ....This project aims to further improve on speech understanding by deaf adults and children using the cochlear implant. In particular, we aim to individually modify the speech coding scheme on the basis of the basic hearing skills of the subject. In this manner, more speech information should be available and the users will likely gain more benefit from their cochlear implants. The speech processing strategy of the multiple-electrode cochlear implant, manufactured by the Australian biomedical company Cochlear Limited, codes acoustic frequency information on electrodes which are located in the cochlea. The assignment of frequencies to electrodes is consistent with the ordering of pitch in the cochlea. For optimum performance, all electrodes would need to be perceptually distinct from each other. Recent research with adults and children has shown that this is not the case for a number of subjects as adjacent electrodes sound the same. Thus important speech information may not be heard by these subjects. In this project, we will determine how well adults and children are able to hear differences between the electrodes, and then provide speech processing schemes which exclude those electrodes which sound the same as others in close proximity. The project will compare these modified strategies with the standard strategy currently used by the subjects over time, so that any differences in the way adults and children are able to improve on speech understanding will be determined. As far as can be determined, this project will be the first investigation to improve on speech understanding in children using the cochlear implant.Read moreRead less
Extraction Of Key Features Of Natural Speech By Ventral Cochlear Nucleus Neurons
Funder
National Health and Medical Research Council
Funding Amount
$225,330.00
Summary
Little is known about how speech is processed and transformed by the central auditory pathway, and how the critical temporal and spectral features that identify a speech sound segment (a phoneme) are extracted. To date, most studies have approached this issue by using synthetic speech and examined the responses of the peripheral auditory nerve only. The aim of this study is to examine how important features of naturally-spoken speech are encoded by the cochlear nucleus (CN) - the first station i ....Little is known about how speech is processed and transformed by the central auditory pathway, and how the critical temporal and spectral features that identify a speech sound segment (a phoneme) are extracted. To date, most studies have approached this issue by using synthetic speech and examined the responses of the peripheral auditory nerve only. The aim of this study is to examine how important features of naturally-spoken speech are encoded by the cochlear nucleus (CN) - the first station in the auditory pathway located in the brainstem. The CN is a complex of different cell types that have the capacity to transmit, transform, and encode complex acoustic information in different ways. The proposed experiments involve recording the bioelectrical signal from single CN cells in anaesthetised rats while presenting naturally-spoken syllables, both in quiet and in the presence of noise. It is important to examine what happens to the neural responses in the latter condition, because all animals must cope with the problem of extracting important signals from background noise. While noise clearly interferes with the perception of another sound, the auditory system is in fact quite good at extracting signals in the presence of noise. This is well demonstrated by our ability to understand speech in the presence of quite high noise levels. This ability is severely degraded in the hearing impaired. Thus, one of the aims of this study is to examine the mechanisms and limits of the CN's ability to encode speech in a noisy background. A greater understanding of the mechanisms the nervous system uses to extract critical features of speech will not only build on our knowledge of auditory brainstem processes, but may also provide clues to improving processing strategies for cochlear implants.Read moreRead less
Auditory Processing Deficits In Specific Language Impairment And Specific Reading Disability:Their Effects And Treatment
Funder
National Health and Medical Research Council
Funding Amount
$314,250.00
Summary
One possible cause of specific language impairment (SLI) and specific reading disability (SRD; commonly known as dyslexia) is an inability to discriminate between sounds. Such an impairment could affect the ability to discriminate between simple speech sounds (phonemes) which are the basic building blocks for developing spoken language and reading skills. How many children with SLI or SRD have poor sound discrimination? What pattern of spoken language and reading impairments do these children ha ....One possible cause of specific language impairment (SLI) and specific reading disability (SRD; commonly known as dyslexia) is an inability to discriminate between sounds. Such an impairment could affect the ability to discriminate between simple speech sounds (phonemes) which are the basic building blocks for developing spoken language and reading skills. How many children with SLI or SRD have poor sound discrimination? What pattern of spoken language and reading impairments do these children have as a result of this impairment? Can poor sound discrimination be fixed? If it can, does it improve spoken language and reading impairments? And if it does, does it have an immediate effect or does it take some time to make a difference? These are some of the questions that will be addressed by this research. The answers will help us develop a training program that focuses specifically on improving the sound discrimination abilities of children who really need it. This will be a more efficient and inexpensive (if not free) than the Fast ForWord program that trains multiple non-verbal and verbal processing abilities regardless of whether a child has an impairment in all (or any) of these abilities and is therefore time consuming (approximately 80 hours) and expensive (approximately $AUD2000). The data will also help up better identify the spoken and written language profiles that characterise children who have sound discrimination deficits so we can better predict whether they would benefit from training programs such as Fast ForWord. And the data will tell use whether impaired sound discrimination can be used to predict whether infants might be at risk for later spoken language and reading problems.Read moreRead less
Improved Perception Of Temporal Information In Electrical Signals For Profoundly Deaf Users Of Cochlear Implants
Funder
National Health and Medical Research Council
Funding Amount
$170,440.00
Summary
The ultimate goal of this project is to improve the ability of cochlear implant users to understand speech. The way in which a speech signal varies in amplitude over time provides useful information to the listener about the content of the speech signal. Currently, the way that the acoustic signal amplitude is converted to electrical signal amplitude for cochlear implantees does not take into consideration the very significant loudness summation present in multiple-electrode electrical stimulati ....The ultimate goal of this project is to improve the ability of cochlear implant users to understand speech. The way in which a speech signal varies in amplitude over time provides useful information to the listener about the content of the speech signal. Currently, the way that the acoustic signal amplitude is converted to electrical signal amplitude for cochlear implantees does not take into consideration the very significant loudness summation present in multiple-electrode electrical stimulation. That is, when there are multiple sequential current pulses on different electrodes over a short time, the resultant loudness is greater than the loudness due to individual current pulses. The lack of consideration of loudness summation effects has led to the amplitude variations in the acoustic signal not being accurately represented in the loudness variation perceived by the cochlear implantee. This project aims to develop a practical way of more accurately representing speech signal amplitude fluctuations for cochlear implantees by studying the effects of loudness summation. A second aim of the project is to study the effects on perception of using differently-shaped current pulses from those currently used. There is evidence from physiology experiments that using different shapes might cause the electrical stimulation to activate a more narrowly-spaced set of auditory neurons for each electrode. The application of results of both these studies will lead directly to improved perception of speech and other sounds by cochlear implantees, thus improving their communication ability and quality of life.Read moreRead less