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At least 253 records · Page 14Linked to original sources
PubMed2004

Criteria of candidacy for unilateral cochlear implantation in postlingually deafened adults III: prospective evaluation of an actuarial approach to defining a criterion.

OBJECTIVE: Outcomes from unilateral cochlear implantation in postlingually deafened adults are variable and difficult to predict precisely from data gathered before surgery. The objective was to derive and validate a method for specifying criteria of candidacy for implantation that takes this variability into account. DESIGN: Accuracy of identifying words in prerecorded sentences without lipreading was measured in 480 users of unilateral multichannel cochlear implants. These patients had all scored zero before surgery on prerecorded open-set tests of word recognition in sentences with acoustic hearing aids. Statistical models were derived that calculated the odds that a patient would score higher with an implant than a criterion score, given knowledge of the duration of profound deafness in the implanted ear. The accuracy of the models was evaluated prospectively with two new groups of patients who scored between 1% and approximately 50% correct before surgery in one or both ears with acoustic hearing aids. Group I (N=53) was implanted in an ear that scored zero. Group II (N=31) was implanted in an ear that scored above zero. Benefits from implantation, measured as changes in word recognition performance and in health utility, were compared with the odds calculated by the statistical models. RESULTS: The preferred model was based on data from 376 subjects. It made accurate predictions of the proportion of patients in group I, and, disregarding minor exceptions, accurate predictions of the proportion of patients in group II, who improved on their preoperative word recognition score. Benefit from implantation was low for patients implanted with odds less favorable than 4:1 (4 chances out of 5). CONCLUSIONS: Adoption of odds of 4:1 as the criterion of candidacy for unilateral cochlear implantation would be likely to maintain acceptable benefit and cost-effectiveness while being explicit and informative for patients, clinicians, and commissioners of health care.

Actuarial Analysis↗
PubMed2006

A role for the inferior colliculus in multisensory speech integration.

Multisensory integration can occur at relatively low levels within the central nervous system. Recent evidence suggests that multisensory audio-visual integration for speech may have a subcortical component, as acoustic processing in the human brainstem is influenced by lipreading during speech perception. Here, stimuli depicting the McGurk illusion (a demonstration of auditory-visual integration using speech stimuli) were presented to a 12-year-old child (FX) with a circumscribed unilateral lesion of the right inferior colliculus. When McGurk-type stimuli were presented in the contralesional hemifield, illusory perception reflecting bimodal integration was significantly reduced compared with the ipsilesional hemifield and a group of age-matched controls. These data suggest a functional role for the inferior colliculus in the audio-visual integration of speech stimuli.

Acoustic Stimulation↗
PubMed2006

Data fusion and multicue data matching by diffusion maps.

Data fusion and multicue data matching are fundamental tasks of high-dimensional data analysis. In this paper, we apply the recently introduced diffusion framework to address these tasks. Our contribution is three-fold: First, we present the Laplace-Beltrami approach for computing density invariant embeddings which are essential for integrating different sources of data. Second, we describe a refinement of the Nyström extension algorithm called "geometric harmonics." We also explain how to use this tool for data assimilation. Finally, we introduce a multicue data matching scheme based on nonlinear spectral graphs alignment. The effectiveness of the presented schemes is validated by applying it to the problems of lipreading and image sequence alignment.

Algorithms↗
PubMed1983

Computerized testing of signal-encoding strategies with round-window implants.

After extensive testing of a patient with two bipolar modiolar electrodes connected to a percutaneous plug in 1977, we provided four patients with a single-channel monopolar round-window electrode connected to a tuned radio-frequency receiver coil. Loudness and pitch discrimination and results of psychophysical scaling experiments of extracochlear electrodes are comparable to those with intracochlear stimulation. Extensive testing with a computerized test system and with tape-recorded and live speech material showed that accurate vowel and speaker identification by stimulation alone is possible and that discrimination by lipreading is considerably improved. Interactive training sessions further improve discrimination results. Different signal-encoding algorithms can be used to generate in real time stimulation signals from prestored speech parameters (such as pitch, gain, formants, and zerocrossing intervals).

Adult↗
PubMed2004

Envelope-onset asynchrony as a cue to voicing in initial english consonants.

An acoustic cue for voicing is proposed based on the underlying processes associated with the production of the voicing contrast. This cue is based on the time asynchrony between the onsets of two amplitude-envelope signals derived from different bands of speech (i.e., envelopes derived from a lowpass-filtered band at 350 Hz and from a highpass-filtered band at 3000 Hz). Acoustic measurements made on the envelope signals of a set of 16 initial consonants represented through multiple tokens of C1VC2 syllables indicate that the onset-timing difference between the low- and high-frequency envelopes (Envelope-Onset Asynchrony or EOA) provides a reliable and robust cue for distinguishing voiced from voiceless consonants. This cue, which is simply derived in real-time, has applications to the design of sensory aids for persons with profound hearing impairments (e.g., as a supplement to lipreading), as well as to automatic speech recognition.

Adult↗
PubMed1983

Evaluation of a tactile vocoder for work recognition.

Normal subjects learned to identify words through a tactile vocoder. The vocoder employed 16 filter channels, each with a bandwidth of 1/3 octave, with center frequencies ranging from 200-8000 Hz. The output of each filter was detected and after logarithmic amplification the resulting outputs were transmitted to a 16-channel solenoid array placed on the subject's ventromedial forearm. Words, spoken "live voice," were used as stimuli; the subject was able to feel both the vocalization of the reader and herself and, most importantly, extensive training was provided. In 40.5 h one subject learned 70 words and a second subject reached criterion on 150 words in the comparatively short time of 55 h. Words that were poorly identified initially were identified more readily with increased experience. Phonetic identification tests showed that the features of voicing, nasality, and frication were reliably recognized, indicating the tactile vocoder will be useful in providing information to complement lipreading. Finally, subjects learned rapidly to generalize word-learning to unfamiliar readers.

Communication Devices for People with Disabilities↗
PubMed1985

A comparison of three speech coding strategies using an acoustic model of a cochlear implant.

Three alternative speech coding strategies suitable for use with cochlear implants were compared in a study of three normally hearing subjects using an acoustic model of a multiple-channel cochlear implant. The first strategy (F2) presented the amplitude envelope of the speech and the second formant frequency. The second strategy (F0 F2) included the voice fundamental frequency, and the third strategy (F0 F1 F2) presented the first formant frequency as well. Discourse level testing with the speech tracking method showed a clear superiority of the F0 F1 F2 strategy when the auditory information was used to supplement lipreading. Tracking rates averaged over three subjects for nine 10-min sessions were 40 wpm for F2, 52 wpm for F0 F2, and 66 wpm for F0 F1 F2. Vowel and consonant confusion studies and a test of prosodic information were carried out with auditory information only. The vowel test showed a significant difference between the strategies, but no differences were found for the other tests. It was concluded that the amplitude and duration cues common to all three strategies accounted for the levels of consonant and prosodic information received by the subjects, while the different tracking rates were a consequence of the better vowel recognition and the more natural quality of the F0 F1 F2 strategy.

Adult↗
PubMed1985

Tactile aids for profoundly deaf children.

This paper treats acoustic-tactile communication aids for the deaf. Children who obtain negligible help from conventional hearing aids are of particular interest. For the prelingually deaf child tactile aids may facilitate the acquisition of lipreading, and improve vocal production. Although attempts to use tactile aids for the deaf go back many years, only recently have developments in technology led to greatly improved processing possibilities and the feasibility of aids that can be worn. Here, we report case studies in which prelingually, profoundly deaf young children used wearable tactile aids.

Child, Preschool↗
PubMed1997

Information from time-varying vibrotactile stimuli.

Experiments have been carried out to investigate the information transfer available via a single vibrator on the fingertip. In a first experiment, for stimuli with durations 80 to 320 ms, discrimination of a one-octave step change in frequency at the halfway point was investigated. Results were similar for three stimulus types--sinewave, monophasic pulse and tetraphasic pulse--suggesting temporal cues are more important than spectral cues in this task. In a second experiment, subjects were required to perceive changes in a sequence of stimulus elements. A presentation rate of 6.25 elements s-1 was found to give better results than a rate of 12.5 elements s-1. In the former case, the potential information transfer per element was estimated to be approximately 1.0 bits, corresponding to an information transfer rate of around 6 bits s-1. Implications for the design of a tactile aid to lipreading are discussed.

Adult↗
PubMed1999

Adaptation by normal listeners to upward spectral shifts of speech: implications for cochlear implants.

Multi-channel cochlear implants typically present spectral information to the wrong "place" in the auditory nerve array, because electrodes can only be inserted partway into the cochlea. Although such spectral shifts are known to cause large immediate decrements in performance in simulations, the extent to which listeners can adapt to such shifts has yet to be investigated. Here, the effects of a four-channel implant in normal listeners have been simulated, and performance tested with unshifted spectral information and with the equivalent of a 6.5-mm basalward shift on the basilar membrane (1.3-2.9 octaves, depending on frequency). As expected, the unshifted simulation led to relatively high levels of mean performance (e.g., 64% of words in sentences correctly identified) whereas the shifted simulation led to very poor results (e.g., 1% of words). However, after just nine 20-min sessions of connected discourse tracking with the shifted simulation, performance improved significantly for the identification of intervocalic consonants, medial vowels in monosyllables, and words in sentences (30% of words). Also, listeners were able to track connected discourse of shifted signals without lipreading at rates up to 40 words per minute. Although we do not know if complete adaptation to the shifted signals is possible, it is clear that short-term experiments seriously exaggerate the long-term consequences of such spectral shifts.

Adolescent↗
PubMed1992

Case report: top hearing performances of a postlingually deaf cochlear implant user.

On the occasion of the Cochlear Implant Symposium in Geneva in October 1991, top hearing results attained by a young postlingually deaf woman with cochlear implant systems were presented in video recordings. These data are centered on demanding hearing performances in test situations and in a telephone conversation. For various reasons, two reimplantations were necessary in this deaf patient. Initially, she was provided with a single-channel extra-cochlear electrode of the Vienna type, which she found to improve her lipreading substantially, and she attained an unexpectedly good understanding of speech on a purely auditory basis. Today, this postlingually deaf women uses a multichannel intracochlear electrode of the Nucleus type. The excellent results with the first extracochlear system are clearly surpassed with the intracochlear system. Not least because of her above-average speech competence, the cochlear implant user attains a high degree of open speech understanding. Her verbal hearing efficiency is comparable to that of a person with mild to moderately severe hearing loss.

Adolescent↗
PubMedDate not supplied

Cochlear implant versus vestibular stimulation. Communication.

Results obtained with cochlear electrode implants in totally deaf patients indicate that this means of transmitting auditory information can be of great help in lipreading and remote sound contact. However, using an alternate approach involving fenestration of the labyrinth and acoustical stimulation of the vestibular nerve, we generated a signal in an animal model superior in quality to that generated by electrical stimulation of the cochlea of the cat. This communication raises the question of whether a vestibular signal could be processed so that a deaf person could hear and identify sounds.

Acoustic Stimulation↗
PubMed1991

Effect of age at onset of deafness on children's speech perception abilities with a cochlear implant.

The speech perception abilities of 37 children with cochlear implants (single-channel or multichannel) were examined as a function of age at onset of deafness. There was no significant difference in the speech perception abilities of implanted children who were born deaf and those of implanted children who lost their hearing during the first 3 years of life. In contrast, the performance of children whose age at onset of deafness was 5 years or later was significantly better than that of the children with congenital or early-acquired deafness on tests of stress pattern categorization, closed-set word identification, open-set identification of common phrases, and lipreading enhancement.

Age Factors↗
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↗
PubMed1993

Auditory brainstem implant: II. Postsurgical issues and performance.

The auditory brainstem implant (ABI) restores some hearing sensations to patients deafened by bilateral acoustic tumors. Electrodes are stable for more than 10 years. In most cases nonauditory side effects can be avoided by judicious selection of the stimulating waveform and electrode configuration. Most perceptual measurements demonstrate that the ABI produces psychophysical and speech performance similar to that of single-channel cochlear implants. ABI patients receive suprasegmental information in speech and significant enhancement of speech understanding when the sound from the ABI is combined with lipreading.

Brain Stem↗
PubMed1976

The cochlear implant; basic principles.

In recent years the cochlear implant has been a subject of much discussion and controversy. The clinician has often been confused by the conflicting reports of success and failure. In this paper the development of the cochlear implant is reviewed and its present status summarized. It is hoped that the clinician may thereby gain an understanding of this device so that he can better evaluate its present and future status. Selection of Patients for Cochlear Implantation. The cochlear implant will benefit only those patients with hair cell loss who have remaining viable auditory neurons. In order to determine whether viable neurons remain, an electric current is passed through a small needle which is place into the promontory through the tympanic membrane. If patients experience an auditory sensation as a result of this electrical stimulation, it is felt that they are suitable candidates for a cochlear implant. Feasibility of Long-Term VIIIth Nerve Stimulation. Many questions have been raised regarding the feasibility of long-term stimulation of the auditory nerve. The first question raised was whether the auditory nerve would survive severe hair cell degeneration. Studies have shown that in most cases at least a few auditory neurons remain. The next question was whether the cochlear implant itself would destroy the remaining auditory neurons. Preliminary studies have shown that the nerve will survive the placement of electrodes both into the modiolus and the scala tympani. Several electrode materials and insulation have been found to be well tolerated, and there has been minimal damage from thermal or electrolytic processes; therefore, it appears feasible to stimulate the auditory nerve over a long period. Information Transfer by Electrical Stimulation. Single-channel stimulation produces only periodicity pitch, and information transfer is insufficient for speech discrimination. Experience to date indicates that it will be possible to produce both place and volley pitch by electrical stimulation with multiple electrodes in the scala tympani. These findings give promise for the feasibility of producing a device which will transfer sufficient information to produce speech discrimination. Present Status of the Cochlear Implant. To the present time 15 patients have been implanted with a unipolar electrode under the direction of the Ear Research Institute. These patients have all benefited from their devices. They are able to perceive background sounds and receive a cadence or rhythm to speech which makes the device helpful in lipreading. None of the patients have developed significant speech discrimination.

Auditory Cortex↗
PubMed1988

Comparative studies of speech processing strategies for cochlear implants.

A wide variety of speech processing strategies for multichannel auditory prostheses were compared in studies of two patients implanted with the UCSF electrode array. Each strategy was evaluated using tests of vowel and consonant confusions, with and without lipreading. Included among the strategies were the compressed analog processor of the present UCSF/Storz prosthesis and a group of interleaved pulses processors in which the amplitudes of nonsimultaneous pulses code the spectral variations of speech. For these patients, each with indications of poor nerve survival, test scores were significantly higher with the interleaved pulses processors. We believe this superior performance was a result of 1. the substantial release from channel interactions provided by nonsimultaneous stimuli and 2. a fast enough rotation among the channels to support adequate temporal and spectral resolution of perceived speech sounds.

Cochlear Implants↗
PubMed2002

Patterns of spelling in young deaf and hard of hearing students.

The study examined the invented spelling abilities demonstrated by kindergarten and first-grade deaf and hard of hearing students. The study included two parts: In Part 1, the researcher compared three groups (deaf, hard of hearing, and hearing) using posttesting only on the Early Reading Screening Inventory, or ERSI (Morris, 1998), and in part 2 collected and analyzed samples of the spelling of deaf students in a Total Communication program. Analysis showed that the deaf group performed significantly differently in three areas: concept of word, word recognition, and phoneme awareness ("invented spelling"; Read, 1971). The deaf group outperformed the hearing and hard of hearing groups in concept of word and word recognition. But in phoneme awareness, the deaf group performed significantly less well than the hearing group. Therefore, the deaf group's spelling was followed for 1 year. Deaf students' spelling patterns were not the same as those of hearing and hard of hearing students. Deaf students' spelling miscues were directly related to the cueing systems of lipreading, signing, and fingerspelling.

Achievement↗