Methylprednisolone applied directly to the round window reduces dizziness after cochlear implantation: a randomized clinical trial.

This prospective, double-blind controlled, randomized clinical trial of 43 adults showed that topical methylprednisolone applied to the round window during cochlear implantation was effective in protecting inner ear function. Postoperative vestibular disturbance was significantly lower in the steroid group (5%) than the control group (29%). Electrode impedances from the middle portion of the electrode array (electrodes 10-13) were significantly reduced in steroid-treated recipients compared to controls. Hearing and vestibular function analyses were under-powered to detect any drug changes due to limited participant data.

Two-component hearing sensations produced by two-electrode stimulation in the cochlea of a deaf patient.

Dissimilarities in perception elicited by stimulation with two electrodes were estimated. A two-dimensional spatial configuration was found to be suitable to represent the dissimilarity data, and the two dimensions could be interpreted as corresponding to the position of the apical and basal electrode of the two-electrode combination. A speech-processing strategy that converts acoustic, first and second formants to two-electrode stimulation is proposed.

Speech recognition for 40 patients receiving multichannel cochlear implants.

We collected data on 40 patients who received the Nucleus multichannel cochlear implant. Results were reviewed to determine if the coding strategy is effective in transmitting the intended speech features and to assess patient benefit in terms of communication skills. All patients demonstrated significant improvement over preoperative results with a hearing aid for both lipreading enhancement and speech recognition without lipreading. Of the patients, 50% demonstrated ability to understand connected discourse with auditory input only. For the 23 patients who were tested 12 months postoperatively, there was substantial improvement in open-set speech recognition.

A multiple-electrode intracochlear implant for children.

A multiple-electrode intracochlear implant that provides 21 stimulus channels has been designed for use in young children. It is smaller than the adult version and has magnets to facilitate the attachment of the headset. It has been implanted in two children aged 5 and 10 years. The two children both lost hearing in their third year, when they were still learning language. Following implantation, it was possible to determine threshold and comfortable listening levels for each electrode pair. This was facilitated in the younger child by prior training in scaling visual and electrotactile stimuli. Both children are regular users of the implant, and a training and assessment program has been commenced.

Speech perception abilities of adult and pediatric Nucleus implant recipients using the Spectral Peak (SPEAK) coding strategy.

A series of 73 postlinguistically deafened adults and 34 prelinguistically deafened children were evaluated with the Spectral Peak (SPEAK) coding strategy of the Nucleus 22-channel cochlear implant. The adults who received consecutive implants demonstrated rapid acquisition of open-set speech recognition skills in the initial postoperative period. Group mean sentence recognition improved to 53.5% (n = 52) after 2 weeks, 62.1% (n = 55) after 1 month, 69.8% (n = 57) after 3 months, and 74.4% (n = 42) after 6 months of use. At the 6-month evaluation interval, 43% of subjects scored greater than 90% on sound-alone sentence recognition in quiet and only one patient (2.4%) scored less than 10%. Mean monosyllabic word recognition was 35.6% after 6 months of use. The 34 prelinguistically deafened children were converted from the Multipeak strategy to Spectral Peak strategy at four large pediatric implant centers. After 6 months of using the new coding strategy, the children demonstrated significant improvements in their speech perception abilities.

Comparison of two cochlear implant speech-processing strategies.

Speech processors extracting either the fundamental frequency (F0) alone, or the fundamental frequency combined with second formant information (F0-F2), have been evaluated on a totally deaf patient using a multiple-channel cochlear implant. A closed set test using 16 spondees and a modified rhyme test showed that for electrical stimulation alone the F0-F2 speech processor was significantly better than the F0 processor. The open set tests using phonetically balanced words and Central Institute for the Deaf everyday sentences showed that for electrical stimulation alone and electrical stimulation combined with lipreading, the results with the F0-F2 speech processor were all significantly better than with the F0 processor. Information transmission for consonant speech features was also better when using the F0-F2 processor.

Results of a preliminary clinical trial on a multiple channel cochlear prosthesis.

Speech discrimination testing was carried out under clinical trial conditions for eight profoundly postlingually deaf adults to assess the efficacy of a newly developed 22-channel cochlear prosthesis and speech processor. Three months postoperatively, these patients showed significantly better results with the cochlear prosthesis than for preoperative testing with a conventional hearing aid or vibrotactile aid (following a 6-month trial with the aid) on each of a series of tests from the Minimal Auditory Capabilities battery. Assessment of lipreading enhancement using standard speech tests, consonant recognition studies, and speech tracking showed significant improvements for each patient when using the cochlear prosthesis. Six patients showed a significant amount of open set speech discrimination without lipreading at levels which have not been reported for single electrode cochlear prostheses. The two patients who performed poorly on these tests both had restricted multiple channel systems due to their disease, one patient being restricted to virtually a single channel system and the other to only ten of the 22 electrodes. These results indicate that this multiple channel cochlear prosthesis has potential as a treatment for profound postlingual deafness over a wide range of etiologies and ages.

Factors predicting postoperative sentence scores in postlinguistically deaf adult cochlear implant patients.

A sample of 64 postlinguistically profoundly to totally deaf adult cochlear implant patients were tested without lipreading by means of the Central Institute for the Deaf (CID) sentence test 3 months postoperatively. Preoperative promontory stimulation results (thresholds, gap detection, and frequency discrimination), age, duration of profound deafness, cause of deafness, lipreading ability, postoperative intracochlear thresholds and dynamic ranges for electrical stimulation, depth of insertion of the electrode array into the scala tympani, and number of electrodes in use were considered as possible factors that might be related to the postoperative sentence scores. A multiple regression analysis with stepwise inclusion of independent variables indicated that good gap detection and frequency discrimination during preoperative promontory testing, larger numbers of electrodes in use, and greater dynamic ranges for intracochlear electrical stimulation were associated with better CID scores. The CID scores tended to decrease with longer periods of profound deafness.

Perception of connected speech without lipreading, using a multi-channel hearing prosthesis.

Four of 13 totally deaf patients implanted with the Nucleus multi-channel hearing prosthesis at the University of Melbourne have demonstrated the ability to understand connected speech without lipreading or other visual cues. These patients were able to repeat verbatim unknown material read by a tester at rates of up to 35 words per minute. They were also able to understand an average of 78% of key words in everyday sentences in ideal acoustic conditions and 51% of equivalent material over the telephone. These results show that with a good proportion of postlingually deaf patients, the multi-channel hearing prosthesis can not only act as an aid to lipreading, but also restore effective speech understanding without lipreading.

Speech perception using a two-formant 22-electrode cochlear prosthesis in quiet and in noise.

A new speech-processing strategy has been developed for the Cochlear Pty. Ltd. 22-electrode cochlear prosthesis which codes an estimate of the first formant frequency in addition to the amplitude, voice pitch and second formant frequencies. Two groups of cochlear implant patients were tested 3 months after implant surgery, one group (n = 13) having used the old (F0F2) processing strategy and the other (n = 9) having used the new (F0F1F2) strategy. All patients underwent similar postoperative training programs. Results indicated significantly improved speech recognition for the F0F1F2 group, particularly on open set tests with audition alone. Additional testing with a smaller group of patients was carried out with competing noise (speech babble). Results for a closed set spondee test showed that patient performance was significantly degraded at a signal-to-noise ratio of 10 dB when using the F0F2 strategy, but was not significantly affected with the F0F1F2 strategy.

A multiple-channel cochlear implant and wearable speech-processor: an audiological evaluation.

Stand audiological tests were administered to a totally deaf multiple-channel cochlear implant patient with a wearable speech-processor in a monitored sound field under the following conditions: a wearable unit activated alone (WA), lipreading with the wearable unit off (LA), and wearable unit activated in combination with lipreading (WL). Thresholds obtained for narrow-band noise signals indicated that the wearable unit allowed the patient to detect a variety of sounds at different frequencies. The results obtained in closed-set word tests and open-set word and sentence tests showed significant improvements in word and sentence scores from LA to WL. In the open-set (C.I.D.) sentence test, the patient scored 22% for LA and 76% for WL. The WL score of 76% correlates with a satisfactory performance in understanding connected speech. The patient also scored 30% correct in a test involving the recognition of environmental sounds.

A comparison of the monothermal and bithermal caloric tests.

This study considered whether the monothermal (MT) caloric test could predict the normality of the full conventional bithermal (BT) caloric test, and therefore be an alternative to full caloric investigation. This would have the advantages of reducing test time and patient discomfort as only two caloric tests would be needed instead of four. 744 BT caloric investigations were examined, and the unilateral weakness and directional preponderance calculated for the BT and the MT stimuli. By defining the BT results as the standard, the false-positive and false-negative results of the MT test were derived. Overall using very strict MT difference criteria of less than 5% and no spontaneous nystagmus, false-negative rates for the cool MT were very low (< 1%) and better than the warm MT (< 7.1%) suggesting that the cool MT was a reliable screen test. However, unacceptably high false-positive rates were produced reflecting more than 3/4 of normal BT results failing the MT criterion. This unacceptable false-positive rate decided against implementing the MT test at our facility. The results of this study however have guided the use of the cool air-stimulus first during BT testing and, when completion of the BT is not possible or inadvisable, satisfying the stringent MT criterion confidently indicates with a probability of > 99% the absence of an abnormal BT result.

Speech perception in a communicative context: an investigation using question/answer pairs.

By diminishing the role of communicative context, traditional tests of speech perception may underestimate or misrepresent the actual speech perception abilities of adults with a hearing impairment. This study investigates this contention by devising an assessment that may better simulate some aspects of "real-life" speech perception. A group of 31 participants with a severe-to-profound hearing impairment took part in a series of speech perception tests while wearing their hearing aids. The tests used question/answer or adjacency pairs, where the stimulus sentence was preceded by a question spoken by the participant. Four conditions were included: (a) where there was no initiating sentence, as in a traditional open-set speech perception test; (b) where the initiating question was neutral (e.g. "Why?"); (c) where there was a disruptive semantic relationship between the question and answer; and (d) where there was a strong contextual relationship between the question and answer. The time delay between the question and answer was also varied. Results demonstrated that in all conditions where there was a preceding question speech perception improved, and increasing the cohesion between the question and the reply improved speech perception scores. Additionally, time delay and the relatedness of the reply interacted. The effects of semantic context appeared to diminish over a 10-s period while other linguistic effects remained more constant. These results indicate the utility of simulating communicative environments within speech perception tests.

Aided speech recognition abilities of adults with a severe or severe-to-profound hearing loss.

Adults with severe or severe-to-profound hearing losses constitute between 11% and 13.5% of the hearing-impaired population. A detailed investigation of the speech recognition of adults with severe (n = 20) or severe-to-profound (n = 14) hearing loss was conducted at The University of Melbourne. Each participant took part in a series of speech recognition tasks while wearing his or her currently fitted hearing aid(s). The assessments included closed-set tests of consonant recognition and vowel recognition, combined with open-set tests of monosyllabic word recognition and sentence recognition. Sentences were presented in quiet and in noise at +10 dB SNR to replicate an environment more typical of everyday listening conditions. Although the results demonstrated wide variability in performance, some general trends were observed. As expected vowels were generally well perceived compared with consonants. Monosyllabic word recognition scores for both the adults with a severe hearing impairment (M = 67.2%) and the adults with a severe-to-profound hearing impairment (M = 38.6%) could be predicted from the segmental tests, with an allowance for lexical effects. Scores for sentences presented in quiet showed additional linguistic effects and a significant decrease in performance with the addition of background noise (from 82.9% to 74.1% for adults with a severe hearing loss and from 55.8% to 34.2% for adults with a severe-to-profound hearing loss). Comparisons were made between the participants and a group of adults using a multiple-channel cochlear implant. This comparison indicated that some adults with a severe or severe-to-profound hearing loss may benefit from the use of a cochlear implant. The results of this study support the contention that cochlear implant candidacy should not rely solely on audiometric thresholds.

Telephone use by a multi-channel cochlear implant patient. An evaluation using open-set CID sentences.

A totally deaf person with a multiple-channel cochlear prosthesis obtained open-set speech discrimination using the telephone. CID Everyday Sentences were presented by telephone to the patient, who repeated an average of 21 per cent of key words correctly on the first presentation, and 47 per cent when a repeat of the sentences was permitted. This result is consistent with the patient's reports of telephone usage.