Speech recognition in elderly cochlear implant recipients

The benefits of cochlear implantation in the adult and paediatric populations are well established. Cochlear implantation in the geriatric population still remains controversial because of the misconception that elderly patients might perform poorly. The purpose of this study was to report the speech performance of 16 patients over 65 years of age implanted with a Nucleus multichannel cochlear implant and to compare it with that of a control group of 14 adults aged between 41 and 59 years. At the 12 months postoperative evaluation, no significant differences were detected on speech performances between the elderly patients and the control group. The mean word recognition scores were 72.5% for the elderly group and 82% for the control group. The mean everyday sentence recognition scores were 72.5% for the elderly group and 85.7% for the control group. Overall, the results are encouraging and demonstrate that the elderly population with profound hearing loss obtain significant benefits from cochlear implantation despite the age-related auditory processing problems.     

Speech recognition by a deaf-blind multichannel cochlear implant patient

A case study of the first deaf-blind patient implanted with a Nucleus 22 channel cochlear prosthesis is presented. The patient's preimplant evaluation data, using a powerful hearing aid and vibro-tactile device, are compared with results obtained 8 months postimplant. Preimplant testing indicated no consistent response to sound. Postimplant testing showed ability to comprehend some open set speech with hearing alone through the cochlear implant including ability to utilize the telephone without a code system. The postimplant data suggest potential benefit for other postlingually deaf-blind individuals from multichannel cochlear stimulation.     

Speech perception scores in cochlear implant recipients: An analysis of ceiling effects in the CUNY sentence test (Quiet) in post-lingually deafened cochlear implant recipients

Objectives: To evaluate the clinical utility of the City University of New York sentence test in a cohort of post-lingually deafened cochlear implants recipients over time.

Methods: 117 post-lingually deafened, Australian English-speaking CI recipients aged between 23 and 98 years (M?=?66 years; SD?=?15.09) were recruited. CUNY sentence test scores in quiet were collated and analysed at two cut-offs, 95% and 100%, as ceiling scores.

Results: CUNY sentence scores ranged from 4% to 100% (M?=?86.75; SD?=?20.65), with 38.8% of participants scoring 95% and 16.5% of participants reaching the 100% scores. The percentage of participants reaching the 95% and 100% ceiling scores increased over time (6 and 12 months post-implantation).

The distribution of all post-operative CUNY test scores skewed to the right with 82% of test scores reaching above 90%.

Discussion: This study demonstrates that the CUNY test cannot be used as a valid tool to measure the speech perception skills of post-lingually deafened CI recipients over time. This may be overcome by using adaptive test protocols or linguistically, cognitively or contextually demanding test materials.

Conclusion: The high percentage of CI recipients achieving ceiling scores for the CUNY sentence test in quiet at 3 months post-implantation, questions the validity of using CUNY in CI assessment test battery and limits its application for use in longitudinal studies evaluating CI outcomes. Further studies are required to examine different methods to overcome this problem.     

Speech recognition with a cochlear implant using triphasic charge-balanced pulses

OBJECTIVE: Typically, symmetrical charge-balanced biphasic current pulses are used in cochlear implants to ensure biological safety. Theoretically, monophasic pulses are more effective, but potentially noxious, stimuli. In this study we charge-balanced such monophasic pulses during selected non-stimulated intervals, effectively leading to triphasic pulses with a 4:1 amplitude ratio between the cathodic and anodic phases. Apart from ensuring safety, this is also expected to reduce power consumption and channel interaction. MATERIAL AND METHODS: Seven experienced Clarion CII cochlear implant users with a multichannel (12-16 channels) monopolar continuous interleaved sampling (CIS) strategy participated in the study. Three different CIS strategies were fitted using the Clarion Research Interface (CRI-2). The reference was an implementation of each subject's own CIS program. The two strategies tested used triphasic pulses on the same channels, one with half-wave rectification (TP-HWR) and one without rectification (TP-NoR) at the input. Directly after fitting (i.e. without any training), speech perception (phoneme score on consonant-vowel-consonant words) was measured in silence (sound-only) and in speech-shaped background noise with signal:noise ratios (SNRs) of +5 and 0 dB. RESULTS: Speech perception with the reference via the CRI-2 was equal to that of the free-field condition with the subjects' own speech processor. With the TP-NoR strategy, speech perception improved significantly (from 89% to 93%) in silence and in the 0-dB SNR condition (from 43% to 49%). With a SNR of +5 dB, performance was stable at approximately 66%. With the TP-HWR strategy, performance increased significantly in the 0- and +5-dB SNR conditions, to 55% and 74%, respectively. Power consumption was reduced in both strategies, to 30% and 36% for TP-HWR and TP-NoR, respectively. CONCLUSION: The new triphasic strategies are most promising, with respect to both their improved speech perception and reduced power requirements. The optimal parameters will have to be identified following long-term use.     

Speech recognition with a cochlear implant using triphasic charge-balanced pulses

Objective Typically, symmetrical charge-balanced biphasic current pulses are used in cochlear implants to ensure biological safety. Theoretically, monophasic pulses are more effective, but potentially noxious, stimuli. In this study we charge-balanced such monophasic pulses during selected non-stimulated intervals, effectively leading to triphasic pulses with a 4:1 amplitude ratio between the cathodic and anodic phases. Apart from ensuring safety, this is also expected to reduce power consumption and channel interaction.

Material and Methods Seven experienced Clarion CII cochlear implant users with a multichannel (12–16 channels) monopolar continuous interleaved sampling (CIS) strategy participated in the study. Three different CIS strategies were fitted using the Clarion Research Interface (CRI-2). The reference was an implementation of each subject's own CIS program. The two strategies tested used triphasic pulses on the same channels, one with half-wave rectification (TP-HWR) and one without rectification (TP-NoR) at the input. Directly after fitting (i.e. without any training), speech perception (phoneme score on consonant–vowel–consonant words) was measured in silence (sound-only) and in speech-shaped background noise with signal:noise ratios (SNRs) of +5 and 0 dB.

Results Speech perception with the reference via the CRI-2 was equal to that of the free-field condition with the subjects’ own speech processor. With the TP-NoR strategy, speech perception improved significantly (from 89% to 93%) in silence and in the 0-dB SNR condition (from 43% to 49%). With a SNR of +5 dB, performance was stable at ≈66%. With the TP-HWR strategy, performance increased significantly in the 0- and +5-dB SNR conditions, to 55% and 74%, respectively. Power consumption was reduced in both strategies, to 30% and 36% for TP-HWR and TP-NoR, respectively.

Conclusion The new triphasic strategies are most promising, with respect to both their improved speech perception and reduced power requirements. The optimal parameters will have to be identified following long-term use.     

Speech recognition in quiet and noise in borderline cochlear implant candidates

The present study 1) examined speech recognition at three intensity levels and in noise for adults with bilateral hearing loss who wore amplification and were referred for cochlear implant evaluation but did not meet current audiological criteria, and 2) compared their performance to cochlear implant recipients using current implant technology. When tested at 70 dB SPL, hearing aid subjects' word and sentence recognition scores were similar to or greater than the scores of cochlear implant recipients. Compared to their implanted peers, however, subjects' scores were significantly poorer at normal (60 dB SPL) and soft (50 dB SPL) presentation levels for words and at soft levels for sentences; detection thresholds were also significantly poorer at 1000 Hz and above. The assessment of candidates at louder-than-normal levels (i.e., 70 dB SPL) may not correctly portray their day-to-day communication struggles.     

Speech processing for cochlear implant prostheses

The transformation of speech into electrical signals which can stimulate the auditory nerve in order to create hearing sensations that carry speech information depends on many factors. These include the limitations imposed by the current state-of-the-art in otological surgery, microelectronic and micromechanical technology, and knowledge of the functioning of the auditory system under both acoustic and electrical stimulation. Sufficient advances have been made in all these areas to enable several research centers to develop cochlear prostheses which give some hearing to certain totally deaf persons. The work of these centers towards the goal of full unaided speech perception via the prosthesis is examined and evaluated.     

Speech recognition outcomes in Mandarin-speaking cochlear implant users with fine structure processing

Conclusion: Mandarin-speaking adults can use the Fine Structure Processing (FSP) coding strategy as well as the Continuous Interleaved Sampling (CIS+) coding strategy. No loss in performance was observed after switch-over. Tone identification improves over time with the FSP coding strategy, which is of benefit to tonal-language users. After some time, fine structure was preferred.

Objective: This study aimed to determine speech perception, tone perception, and the subjective preferences of Mandarin-speaking adults who received the FSP coding strategy, at upgrade from the CIS?+?coding strategy.

Methods: Thirteen Mandarin-speaking subjects were tested at switch-over from CIS?+?to the FSP coding strategy ～1-month after switch-over, 2-months after switch-over, and 3-months after switch-over with the Mandarin Hearing in Noise Test (M-HINT), the Mandarin Tone Identification in Noise Test (M-TINT), and a visual analogue scale assessing Sound and Speech Assessment (SSA).

Results: There were no significant differences in the M-HINT between presentation levels (62?dB SPL vs 65?dB SPL), over time, nor when compared to the CIS?+?coding strategy. Tone perception improved significantly over time with the FSP coding strategy. Subjects rated the FSP coding strategy with the OPUS 2 as significantly more ‘full’ and ‘rich’ than with the CIS?+?coding strategy after 3-months.     

Speech therapy with cochlear implant wearers

The speech production of three post-lingually deafened adults, who derived no benefit from wearing hearing aids, was assessed. Individual therapy programmes were devised based on these assessments and the subjects participated in a course of speech therapy. They then received cochlear implants and had a further course of speech therapy using their implants. Changes in speech production were judged by trained listeners, who heard tape-recorded samples of the subjects' speech. These samples were taken at various intervals before and after therapy alone, and with the cochlear implant. Significant improvement was heard in the speech production of two of the subjects following speech therapy alone. All three subjects were judged to have improved production of speech after using their cochlear implants for 6 months.     

Speech recognition for unilateral and bilateral cochlear implant modes in the presence of uncorrelated noise sources

OBJECTIVE: The purpose of the current investigation was to compare speech recognition in noise for bilateral and unilateral modes within postlingually deafened, adult bilateral cochlear implant recipients. In addition, it was of interest to evaluate the time course of the bilateral speech-recognition advantage and the effect of changing signal-to-noise ratio (SNR) on the magnitude of the bilateral advantage. DESIGN: In the first experiment, 16 postlingually deafened adults who were bilaterally implanted with the MED-EL C40+ cochlear device were evaluated in unilateral left, unilateral right, and bilateral conditions 4 to 7 mo after activation. Speech recognition in the presence of five spatially separated, uncorrelated noise sources was evaluated using both a single fixed SNR of +10 dB and an adaptive-SNR method. In a follow-up study, a subset of 10 participants was re-evaluated using an identical fixed-SNR method 12 to 17 mo after activation to examine the time course of speech-recognition performance in both unilateral and bilateral modes at a single SNR. A third study was performed with a subset of six participants to examine performance over a range of SNRs. In this study, speech recognition was measured 12 to 17 mo after activation in quiet and at +5, +10, +15, and +20 dB SNRs using the same five uncorrelated noise sources. RESULTS: The speech-recognition data revealed a significant bilateral advantage of 3.3 dB using the adaptive-SNR method. A significant bilateral advantage of 9% was also measured using a fixed +10 dB SNR. Results from the second study revealed that experience resulted in a significant (11 to 20%) increase in speech-recognition-in-noise performance for both unilateral and bilateral modes; however, the magnitude of the bilateral advantage was not affected by experience. Results from the third study revealed the largest bilateral advantage at the poorest SNR evaluated. In addition, performance in quiet was significantly better than that measured in the presence of noise, even at the +20 dB SNR. CONCLUSIONS: The results of these experiments support a small but significant bilateral speech-recognition-in-noise advantage for cochlear implant recipients in an environment with multiple noise sources. This advantage is presumed to be attributable to the combined effects of binaural squelch and diotic summation. Although experience generally improved speech-recognition-in-noise performance in both unilateral and bilateral modes, a consistent bilateral advantage (approximately 10%) was measured at 4 to 7 mo and at 12 to 17 mo postactivation.     

Residual speech recognition and cochlear implant performance: effects of implantation criteria.

OBJECTIVE: This study aimed to determine the effects of preoperative speech reception on postoperative speech recognition with a cochlear implant and to develop a statistical index allowing prediction of postoperative speech recognition before implantation. STUDY DESIGN: The study design was a retrospective case review with statistical modeling. SETTING: The study was conducted at a tertiary referral center with an associated Veteran's Administration hospital. PATIENTS: Postlingually deafened adults with and without residual speech reception participated. INTERVENTION: Cochlear implantation with Cochlear Corporation CI-22 and CI-24 devices was performed. MAIN OUTCOME MEASURES: Monosyllabic word recognition was measured. RESULTS: Duration of deafness and preoperative sentence recognition are both significant predictors of word recognition with a cochlear implant and can account for 80% of the variance in word recognition. CONCLUSIONS: Cochlear implant outcomes are variable but predictable within specific ranges.     

Speech perception and language criteria for paediatric cochlear implant candidature

Existing criteria for cochlear implantation of children with impaired hearing aim to select children who will eventually achieve better speech perception scores with an implant than with a hearing aid. It is difficult to predict the eventual outcomes with hearing aid and implant because speech perception scores typically increase with age, and because the distribution of scores for implant and hearing aid users overlap considerably at all ages. This paper shows how speech perception scores can be combined with spoken language measures to arrive at an objective criterion for implant selection. The method also allows estimation of the likely increase in speech perception score within a few months of implantation and estimation of the probability that the child will perform better with the implant than the hearing aid. The criteria were based on data from 135 evaluations of 50 children using cochlear implants with monosyllabic words, open-set sentences, the Clinical Evaluation of Language Fundamentals, and the Peabody Picture Vocabulary Test. Data from 114 evaluations of 43 children using hearing aids were used to illustrate the sensitivity of the criteria.     

Incorporating ceiling effects during analysis of speech perception data from a paediatric cochlear implant cohort

Objective: To compare speech perception between children with a different age at cochlear implantation. Design: We evaluated speech perception by comparing consonant–vowel–consonant (auditory) (CVC(A)) scores at five-year follow-up of children implanted between 1997 and 2010. The proportion of children from each age-at-implantation group reaching the 95%CI of CVC(A) ceiling scores (>95%) was calculated to identify speech perception differences masked by ceiling effects. Study sample: 54 children implanted between 8 and 36 months. Results: Although ceiling effects occurred, a CVC(A) score difference between age-at-implantation groups was confirmed (H (4)?=?30.36; p?p?<0.001). A larger proportion of children implanted before 13 months compared to children implanted between 13 and 18 months reached ceiling scores. Logistic regression confirmed that age at implantation predicted whether a child reached a ceiling score. Conclusions: Ceiling effects can mask thorough delineation of speech perception. However, this study showed long-term speech perception outperformance of early implanted children (<18 months) either including or not accounting for ceiling effects during analysis. Development of long-term assessment tools not affected by ceiling effects is essential to maintain adequate assessment of young implanted infants.     

Speech recognition ability as a function of duration of deafness in multichannel cochlear implant patients

Surgical implantation of a multichannel cochlear prosthesis has become a widespread treatment for profound hearing loss. The relationship between duration of hearing loss and speech recognition ability was examined in 20 postlinguistically deafened adults using the Nucleus 22-Channel Cochlear Prosthesis. Data analysis indicated statistically significant negative correlations between duration of profound hearing loss and postoperative performance on the Central Institute for the Deaf Everyday Sentence Test and the Northwestern University Monosyllabic Word Test (NU-6). Age at implantation and age at onset of profound hearing loss were not found to be significantly correlated with performance on the two measures. These findings are discussed in terms of patient counseling and prediction of potential benefit to the patient.     

Speech perception by four single-channel cochlear implant users

Four profoundly deaf adults, each a recent recipient of a scala tympani implant, underwent auditory and auditory-visual speech comprehension evaluations. Two subjects had multiple-electrode auditory prostheses, and 2 had single-electrode implants. All subjects were tested preoperatively with a high-power hearing aid, and postoperatively with a single-channel wearable sound processor. Reported here are the results of the first formal speech recognition tests which were conducted during the 8 months after the sound processor fitting. Three subjects had used the single-channel processor on a daily basis for up to 8 months at the time of postoperative testing. The 4th subject was a nonuser. On listening tests, a comparison between pre- and post-implant scores revealed little difference for any subject. On postoperative speechreading tasks, all subjects identified medial consonant phonemes and 2-digit numerals better with stimulation than without. The 3 frequent users of the device experienced significant improvement on connected-discourse tracking, and their speechreading of videotaped and live voice CID Everyday Sentences (Davis & Silverman, 1978) was enhanced with the addition of stimulation. The nonuser was a very proficient speechreader at the outset and exhibited no significant difference on connected-discourse tracking with and without stimulation. Moreover her ability to speechread Everyday Sentences was hampered slightly by the addition of stimulation. This single-channel sound processor functioned as a sensory supplement for the 3 frequent users, but no subject was able to use the processor as a sensory substitute.     

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.     

Speech recognition scores and ABR in cochlear impairment

The relationship between the speech recognition scores (SRS) in noise and the auditory brain-stem evoked response (ABR) was examined in 7 males (age range: 40 to 60 yrs) with fairly similar audiograms but different SRS. The Spearman rank-order correlation coefficient revealed a significant relationship between SRS and latencies of waves I and II of the ABR. The results are discussed in terms of neural degeneration and representation of speech stimuli in the auditory nerve.