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D K Eddington

Publications and source records attributed to D K Eddington.

10 recordsLinked to original sources
PubMed1992

Relations among different measures of speech reception in subjects using a cochlear implant.

A comprehensive set of speech reception measures were obtained in a group of about 20 postlingually deafened adult users of the Ineraid multichannel cochlear implant. The measures included audio, visual, and audiovisual recognition of words embedded in two types of sentences (with differing degrees of difficulty) and audio-only recognition of isolated monosyllabic words, consonant identification (12 alternatives, /Ca/), and vowel identification (8 alternatives, /bVt/). For most implantees, the audiovisual gains in the sentence tests were very high. Quantitative relations among audio-only scores were assessed using power-law transformations suggested by Boothroyd and Nittrouer [J. Acoust. Soc. Am. 84, 101-114 (1988)] that can account for the benefit of sentence context (via a factor k) and the relation between word and phoneme recognition (via a factor j). Across the broad range of performance that existed among the subjects, substantial order was observed among measures of speech reception along the continuum from recognition of words in sentences, words in isolation, speech segments, and the retrieval of underlying phonetic features. Correlations exceeded 0.85 among direct and sentence-derived measures of isolated word recognition as well as among direct and word-derived measures of segmental recognition. Results from a variety of other studies involving presentation of limited auditory signals, single-channel and multichannel implants, and tactual systems revealed a similar pattern among word recognition, overall consonant identification performance, and consonantal feature recruitment. Finally, improving the reception of consonantal place cues was identified as key to producing the greatest potential gains in speech reception.

Adult↗
PubMed1991

Better speech recognition with cochlear implants.

HIGH levels of speech recognition have been achieved with a new sound processing strategy for multielectrode cochlear implants. A cochlear implant system consists of one or more implanted electrodes for direct electrical activation of the auditory nerve, an external speech processor that transforms a microphone input into stimuli for each electrode, and a transcutaneous (rf-link) or percutaneous (direct) connection between the processor and the electrodes. We report here the comparison of the new strategy and a standard clinical processor. The standard compressed analogue (CA) processor presented analogue waveforms simultaneously to all electrodes, whereas the new continuous interleaved sampling (CIS) strategy presented brief pulses to each electrode in a nonoverlapping sequence. Seven experienced implant users, selected for their excellent performance with the CA processor, participated as subjects. The new strategy produced large improvements in the scores of speech reception tests for all subjects. These results have important implications for the treatment of deafness and for minimal representations of speech at the auditory periphery.

Cochlear Implants↗
PubMed1988

Treatment of sensorineural hearing loss by cochlear implantation.

Cochlear implantation, a form of neural prosthesis, is now being employed for some profoundly deaf individuals. The pathophysiology of profound deafness, the strategies inherent in cochlear implantation, the differences between various cochlear implant strategies and designs, medical and otologic evaluation of implant candidates, and the surgical procedure are each discussed. The results in speech recognition and speech reading that have been obtained with four commonly used cochlear implant systems are also presented.

Cochlear Implants↗
PubMed1985

Speech recognition experience with multichannel cochlear implants.

Four patients received multichannel intracochlear implants before 1978 as part of the University of Utah program. By 1983, sound coding strategies and electronic miniaturization were developed to allow production and use of a portable sound processor/cochlear stimulator unit. Approval for expanded clinical trials has allowed implantation of five additional patients by August 1984. Data on the earlier patients demonstrate stability of electrode thresholds and impedance, low risk of the percutaneous pedestal, and the development of speech recognition scores of greater than 60% with electrical stimulation alone and greater than 90% with electrical stimulation combined with lipreading. Data on recent recipients indicate early electrode threshold stability, lower thresholds for apical electrodes, possibility of replacing single-channel with multi-channel units, and low morbidity of the implantation. Return to function in a verbally communicating environment has been achieved by one earlier patient.

Adult↗
PubMed1975

Artifical hearing for the deaf by cochlear stimulation: pitch modulation and some parametric thresholds.

The periodicity and place-pitch modulation data, along with the data on loudness, offers promise of the development of a multielectrode, multichannel cochlear auditory prosthesis. Also, the currents required for cochlear stimulation are of the magnitude which can pass across the electrode-perilymph interface, by double-layer charging, without production of toxic by-products of electrolysis(6), supporting the feasibility of long-term chronic stimulation.

Acoustic Stimulation↗
PubMedDate not supplied

Fundamental considerations in designing auditory implants.

The usual premise underlying developmental work on cochlear prostheses as prospective cures for profound deafness is that the auditory nerve can be electrically stimulated in such a manner that communicative skills can be developed or maintained. Physiologic recordings from single fibers in the cat's auditory nerve and attempts to model these responses have generated a description of how the auditory nerve codes complex sounds such as speech. This work suggests that certain minimal cues might have to be present at the level of the auditory nerve in order that adequate discrimination of specific speech signals can take place. The prospects for achieving a useful prosthesis in the near future will be evaluated in terms of what can be expected from current attempts to code the artificial stimulation properly.

Acoustic Stimulation↗
PubMedDate not supplied

Auditory prostheses research with multiple channel intracochlear stimulation in man.

Although single-channel electrode arrays implanted in the scala tympani of deaf patients are useful as an aid to lip reading and for distinguishing some environmental sounds, they do not transmit intelligible speech. However, multichannel electrode arrays, which take advantage of the cochlea's tonotopic organization, may be capable of generating the complex patterns of neural activity necessary for speech discrimination. In this study, multichannel electrodes were implanted in the cochleas of four volunteers, with access to the connecting wires made through the skin via a percutaneous connector. The major portion of the data presented is from two of these subjects: one has been bilaterally deaf since birth and the other has been unilaterally deaf for 15 years. Preliminary results of experiments with two more recently implanted subjects are described as well as experiments with a fifth volunteer who was implanted with five electrodes by House in 1969. Data on pitch and loudness discrimination as well as the effects of stimulation parameters on threshold, impedance, and electrode interaction are presented. Place pitch and periodicity pitch were observed in all five volunteers. The results of pitch-matching experiments with the unilaterally deaf volunteer were consistent with tonotopic maps of the cochlea, and experiments indicated that a pitch continuum may be achieved by combining place and periodicity pitch modulation. Preliminary experiments in tune recognition with one subject demonstrate his ability to recognize simple melodies based on periodicity pitch cues. These results, coupled with the finding that subjective sensations remain stable over the long-term, support the feasibility of providing artificial hearing with a multichannel cochlear stimulation system.

Acoustic Stimulation↗