Relationships Between Speech, Spatial and Qualities of Hearing Short Form SSQ12 Item Scores and their Use in Guiding Rehabilitation for Cochlear Implant Recipients.

Cochlear implantation successfully improves hearing in most adult recipients. However, in rare cases, post-implant rehabilitation is required to maximize benefit. The primary aim of this investigation was to test if self-reports by cochlear implant users indicate the need for post-implant rehabilitation. Listening performance was assessed with the Speech, Spatial and Qualities short-form SSQ12, which was self-administered via a web-based survey. Subjects included over 2000 adult bilateral or unilateral cochlear implant users with at least one year of experience. A novel application of regression tree analysis identified core SSQ12 items that serve as first steps in establishing a plan for further rehabilitation: items 1, 8, and 11 dealing with single-talker situations, loudness perception, and clarity, respectively. Further regression and classification tree analyses revealed that SSQ12 item scores were weakly related to age, degree of tinnitus, and use of bilateral versus unilateral implants. Conversely, SSQ12 scores were strongly associated with self-rated satisfaction and confidence in using their cochlear implant. The SSQ12 total scores did not vary significantly over 1-9 or more years' experience. These findings suggest that the SSQ12 may be a useful tool to guide rehabilitation at any time after cochlear implantation. Identification of poor performance may have implications for timely management to improve the outcomes, through various techniques such as device fitting adjustments, counseling, active sound exposure, and training spatial hearing.

Longitudinal outcomes for educational placement and quality of life in a prospectively recruited multinational cohort of children with cochlear implants.

OBJECTIVES: The aim of this study was to report on the educational placement, quality of life and speech reception changes in a prospectively recruited group of children after they received a cochlear implant (CI). METHOD: Data was collected on 1085 CI recipients of as part of a prospective, longitudinal, observational, international, multi-centre, paediatric registry, initiated by Cochlear Ltd (Sydney, NSW, Australia). Outcome data from children (≤10 years old) implanted in routine practice was voluntarily entered into a central, externally hosted, e-platform. Collection occurred prior to initial device activation (baseline) and at six monthly follow-up intervals up to 24 months and then at 3 years post activation. Clinician reported baseline and follow up questionnaires and Categories of Auditory Performance version II (CAP-II) outcomes were collated. Self-reported evaluation forms and patient information were provided by the parent/caregiver/patient via the implant recipient baseline and follow up, Children Using Hearing Implants Quality of Life (CuHIQoL) and Speech Spatial Qualities (SSQ-P) Parents Version questionnaires. RESULTS: Children were mainly bilaterally profoundly deaf, unilaterally implanted and used a contralateral hearing aid. Prior to implant 60% used signing or total communication as their main mode of communication. Mean age at implant was 3.2 ± 2.2 years (range 0-10 years). At baseline 8.6% were in mainstream education with no additional support and 82% had not yet entered school. After three years of implant use, 52% had entered mainstream education with no additional support and 38% had not yet entered school. In the sub-group of 141 children who were implanted at or after three years of age and were thus old enough to be in mainstream school at the three-year follow up, an even higher proportion (73%) were in mainstream education with no support. Quality of life scores for the child improved statistically significantly post implant compared to baseline and continued to improve significantly at each interval up to 3 years (p < 0.001). Parental expectation scores reduced statistically significantly from baseline compared to all intervals (p < 0.028) and then increased significantly at 3 years compared to all post baseline follow-up intervals (p < 0.006). The impact on family life was reduced post implant compared to baseline and continued to reduce between annual intervals (p < 0.001). At three years post follow up median CAP II scores were 7 (IQR 6-7) and mean SSQ-P scores were 6.8 (SD1.9) 6.0 (SD1.9) and 7.4 (SD 2.3) for speech spatial and qualities scales respectively. SSQ-P and CAP II scores improved statistically and clinically significantly compared to baseline by one year post implantation. CAP II scores continued to improve at each test interval up to three years post implant. Speech and Qualities scores improved significantly between years 1 and 2 (p < 0.001), but only the Speech scores improved significantly between years 2 and 3 (p = 0.004). CONCLUSIONS: Mainstream educational placement was achievable for most of the children, including those implanted at an older age. Quality of life for the child and the wider family improved. Future research could focus on the impact of mainstream school placement on children's academic progress, including measures of academic attainment and social functioning.

Auditory cortical plasticity after cochlear implantation in asymmetric hearing loss is related to spatial hearing: a PET H215O study.

In asymmetric hearing loss (AHL), the normal pattern of contralateral hemispheric dominance for monaural stimulation is modified, with a shift towards the hemisphere ipsilateral to the better ear. The extent of this shift has been shown to relate to sound localization deficits. In this study, we examined whether cochlear implantation to treat postlingual AHL can restore the normal functional pattern of auditory cortical activity and whether this relates to improved sound localization. The auditory cortical activity was found to be lower in the AHL cochlear implanted (AHL-CI) participants. A cortical asymmetry index was calculated and showed that a normal contralateral dominance was restored in the AHL-CI patients for the nonimplanted ear, but not for the ear with the cochlear implant. It was found that the contralateral dominance for the nonimplanted ear strongly correlated with sound localization performance (rho = 0.8, P < 0.05). We conclude that the reorganization of binaural mechanisms in AHL-CI subjects reverses the abnormal lateralization pattern induced by the deafness, and that this leads to improved spatial hearing. Our results suggest that cochlear implantation enables the reconstruction of the cortical mechanisms of spatial selectivity needed for sound localization.

Stimulation Rate and Voice Pitch Perception in Cochlear Implants.

The stimulation rate in cochlear implant (CI) sound coding, or the "carrier" rate in pulses per second (pps), is known to influence pitch perception, as well as loudness perception and sound quality. Our main objective was to investigate the effects of reduced carrier rate on the loudness and pitch of coded speech samples. We describe two experiments with 16 Nucleus® CI users, where we controlled modulation characteristics and carrier rate using Spectral and Temporal Enhanced Processing (STEP), a novel experimental multichannel sound coder. We used a fixed set of threshold and comfortable stimulation levels for each subject, obtained from clinical MAPs. In the first experiment, we determined equivalence for voice pitch ranking and voice gender categorization between the Advanced Combination Encoder (ACE), a widely used clinical strategy in Nucleus® recipients, and STEP for fundamental frequencies (F0) 120-250 Hz. In the second experiment, loudness was determined as a function of the input amplitude of speech samples for carrier rates of 1000, 500, and 250 pps per channel. Then, using equally loud sound coder programs, we evaluated the effect of carrier rate on voice pitch perception. Although nearly all subjects could categorize voice gender significantly above chance, pitch ranking varied across subjects. Overall, carrier rate did not substantially affect voice pitch ranking or voice gender categorization: as long as the carrier rate was at least twice the fundamental frequency, or when stimulation pulses for the lowest, 250 pps carrier were aligned to F0 peaks. These results indicate that carrier rates as low as 250 pps per channel are sufficient to support functional voice pitch perception for those CI users sensitive to temporal pitch cues; at least when temporal modulations and pulse timings in the coder output are well controlled by novel strategies such as STEP.

Influence of tinnitus annoyance on hearing-related quality of life in cochlear implant recipients.

Tinnitus is a common symptom in cochlear implant (CI) recipients. There is no clear evidence of the influence of tinnitus on hearing-related quality of life (QoL) in this population. The aim of this study was to assess the relationship between hearing-related QoL measured by the Speech, Spatial and Qualities of Hearing scale (SSQ12) and tinnitus annoyance or perceived change in tinnitus annoyance after cochlear implantation. The study sample consisted of 2322 implanted adults across France, Germany, Ireland, Italy, the Netherlands, Sweden and the United Kingdom. Information relating to QoL measured using the SSQ12 and tinnitus annoyance and change in tinnitus annoyance, assessed using single-item questions, were collected one or more years post-implantation. The relationship between SSQ12 score and tinnitus annoyance or change in tinnitus annoyance was analysed using linear models adjusted for age and unilateral versus bilateral implants. Tukey pairwise tests were used to compare mean SSQ12 scores across levels of tinnitus annoyance and changes. Tinnitus prevalence was 33.9% post-implantation. Recipients with tinnitus had a significantly lower SSQ12 score than recipients without tinnitus. SSQ scores varied significantly with tinnitus annoyance, age and unilateral versus bilateral implants. Overall, CI recipients who experienced less bothersome tinnitus reported better hearing-related QoL. Healthcare professionals should be aware of the influence of tinnitus on CI recipients' hearing to manage patient expectations.

The Listening Network and Cochlear Implant Benefits in Hearing-Impaired Adults.

Older adults with mild or no hearing loss make more errors and expend more effort listening to speech. Cochlear implants (CI) restore hearing to deaf patients but with limited fidelity. We hypothesized that patient-reported hearing and health-related quality of life in CI patients may similarly vary according to age. Speech Spatial Qualities (SSQ) of hearing scale and Health Utilities Index Mark III (HUI) questionnaires were administered to 543 unilaterally implanted adults across Europe, South Africa, and South America. Data were acquired before surgery and at 1, 2, and 3 years post-surgery. Data were analyzed using linear mixed models with visit, age group (18-34, 35-44, 45-54, 55-64, and 65+), and side of implant as main factors and adjusted for other covariates. Tinnitus and dizziness prevalence did not vary with age, but older groups had more preoperative hearing. Preoperatively and postoperatively, SSQ scores were significantly higher (Δ0.75-0.82) for those aged <45 compared with those 55+. However, gains in SSQ scores were equivalent across age groups, although postoperative SSQ scores were higher in right-ear implanted subjects. All age groups benefited equally in terms of HUI gain (0.18), with no decrease in scores with age. Overall, younger adults appeared to cope better with a degraded hearing before and after CI, leading to better subjective hearing performance.

Factors contributing to clinically important health utility gains in cochlear implant recipients.

PURPOSE: Cochlear implantation can restore access to sound and speech understanding in subjects with substantial hearing loss. The Health Utilities Index Mark III (HUI3) measures the impact of an intervention on the patient's quality of life and is sensitive to changes in hearing. In the current study we used factor analysis to predict a clinically important gain in HUI3 scores in adult cochlear implant recipients. METHODS: Data were collected in an observational study for 137 adult recipients from a single center who had at least 1-year HUI3 follow-up. Demographic and other baseline parameters were retrospectively analyzed for their association with a clinically important HUI3 scale gain, defined as at least 0.1 points. Data were also collected for the speech spatial qualities (SSQ) scale. RESULTS: Baseline telephone use and HUI3 hearing, speech and emotion attribute levels were significantly associated with clinically important gains in HUI3 scores. However, SSQ scores increased significantly with or without clinically important HUI3 gains. CONCLUSION: Those subjects who were unhappy or experienced difficulties communicating with strangers or in a group were twice as likely to obtain a clinically important gain in health utility compared to those who were happy or had less difficulty communicating. Subjects who were unable to use the telephone prior to cochlear implantation were one and a half times more likely to obtain a clinically important gain. The SSQ scale was more sensitive to hearing improvements due to cochlear implantation. An inability to use the telephone is an easy to assess biomarker for candidacy for cochlear implantation.

Evidence of a functional reorganization in the auditory dorsal stream following unilateral hearing loss.

Unilateral hearing loss (UHL) generates a disruption of binaural hearing mechanisms, which impairs sound localization and speech understanding in noisy environments. We conducted an original study using fMRI and psychoacoustic assessments to investigate the relationships between the extent of cortical reorganization across the auditory areas for UHL patients, the severity of unilateral hearing loss, and the deficit in binaural abilities. Twenty-eight volunteers (14 UHL patients) were recruited (twenty-two females and six males). The brain imaging analysis demonstrated that UHL induces a shift in aural dominance favoring the better ear, with a cortical reorganization located in the non-primary auditory areas, ipsilateral (same side) to the better ear. This reorganization is correlated not only to the hearing loss severity but also to spatial localization abilities. A regression analysis between brain activity and patient's performance clearly showed that the spatial hearing deficit was linked to a functional alteration of the posterior auditory areas known to process spatial hearing. Altogether, our study reveals that UHL alters the dorsal auditory stream, which is deleterious to spatial hearing.

Early Sentence Recognition in Adult Cochlear Implant Users.

OBJECTIVE: Normal-hearing subjects listening to acoustic simulations of cochlear implants (CI) can obtain sentence recognition scores near 100% in quiet and in 10 dB signal-to-noise ratio (SNR) noise with acute exposure. However, average sentence recognition scores for real CI listeners are generally lower, even after months of experience, and there is a high degree of heterogeneity. Our aim was to identify the relative importance and strength of factors that prevent CI listeners from achieving early, 1-mo scores as high as those for normal-hearing-listener acoustic simulations. DESIGN: Sentence recognition scores (100 words/list, 65 dB SPL) using CI alone were collected for all adult unilateral CI listeners implanted in our center over a 5-yr period. Sentence recognition scores in quiet and in 10 dB SNR 8-talker babble, collected from 1 to 12 mo, were reduced to a single dependent variable, the "initial" score, via logarithmic regression. "Initial" scores equated to an improved estimate of 1-mo scores, and integrated the time to rise above zero score for poorer performing subjects. Demographic, device, and medical data were collected for 118 subjects who met standard CI candidacy criteria. Computed tomography of the electrode array allowing determination of the insertion depth as an angle, and the presence or absence of scala dislocation was available for 96 subjects. Predictive factors for initial scores were selected using stepwise multiple linear regression. The relative importance of predictive factors was estimated as partial r with a low bias method, and statistical significance tested with type II analysis of variance. RESULTS: The etiologies chronic otitis and autoimmune disease were associated with lower, widely variable sentence recognition scores in the long-term. More than 60% of CI listeners scored >50/100 in quiet at 1 mo. Congenital hearing loss was associated with significantly lower initial scores in quiet (r 0.23, p < 0.001), as was longer duration of hearing loss (r 0.12, p < 0.001, -0.76 pts per year). Initial scores were negatively correlated with insertion depth (r 0.09, p < 0.001, -0.1 pts per degree), with the highest initial scores being obtained for insertion depths of 300° to 400°. A much greater proportion of scala dislocations was found for perimodiolar arrays compared with straight arrays. Scores were negatively correlated with the proportion of the active electrode array found in scala vestibuli for Nucleus perimodiolar devices (r 0.14, p < 0.01, coefficient -25). Similar overall results were obtained for sentence recognition scores in noise (+10 dB SNR). The intercept value for the obtained regression functions indicated that CI listeners with the least limiting factors generally scored ~95/100 in quiet and ~90/100 in noise. In addition, CI listeners with insertion angles as low as 315° to 360° could obtain sentence recognition scores >80/100 even at 1 day after activation. Insertion depths of 360° were estimated to produce frequency-place mismatches of about one octave upward shift. CONCLUSIONS: Patient-related factors etiology and duration of deafness together explained ~40% of the variance in early sentence recognition scores, and electrode position factors ~20%. CI listeners with insertion depths of about one turn obtained the highest early sentence recognition scores in quiet and in noise, and these were comparable with those reported in the literature for normal-hearing subjects listening to 8 to 12 channel vocoder simulations. Differences between device brands were largely explained by differences in insertion depths. This indicates that physiological frequency-place mismatches of about one octave are rapidly accommodated by CI users for understanding sentences, between 1 day to 1 mo postactivation, and that channel efficiency may be significantly poorer for more deeply positioned electrode contacts.

Objective, audiological and quality of life measures with the CI532 slim modiolar electrode.

OBJECTIVES: To report on electrode array measurements for the Nucleus® CI532 Slim Modiolar Electrode device including: ECAP thresholds, electrode impedances, and psychophysical comfort levels, as well as speech perception results pre- and post-operatively and standardized evaluations of quality of life. METHODS: Forty-four subjects were implanted with the CI532. Electrically evoked compound action potential (ECAP) thresholds and impedances were measured using automatic Neural Response Telemetry intra-operatively, at activation and at six months post implant. Pre- and post-operative measures of words in quiet and sentences in noise were made in multiple languages. Quality of life was assessed using The Speech Spatial Qualities questionnaire (SSQ) and Glasgow Benefit Inventory (GBI). RESULTS: Intra-operative ECAP thresholds were recorded successfully from 90% of electrodes tested. ECAP thresholds varied across the array and a post-hoc Dunn's test showed that median thresholds for electrodes E1-E13 were significantly greater than those for E17-E22 (all P < 0.001). Impedances increased significantly between surgery and activation. Speech recognition scores for words in quiet and sentences in noise showed a significant improvement for the group at six months, when using the cochlear implant, compared with pre-operative performance (P < 0.001). There was a significant increase compared to pre-operative ratings for all sections of the SSQ at six months post activation (P < 0.001). The GBI gave scores significantly above zero for the 'general' subscale and total score. CONCLUSION: Objective ECAP and impedance measures for this new electrode array were as expected and similar to results reported for other array types. Speech perception and quality of life improved significantly following implantation. (Registered as NCT02392403 on ClinicalTrials.gov PRS).

Clinical investigation of the Nucleus Slim Modiolar Electrode.

AIMS: The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography. METHODS: Forty-five adult candidates for unilateral cochlear implantation were recruited from 8 centers. Eleven surgeons attended a temporal bone workshop and received further training with a transparent plastic cochlear model just prior to the first surgery. Feedback on the surgical approach and use of the SME was collected via a questionnaire for each case. Computed tomography of the temporal bone was performed postoperatively using flat-panel digital volume tomography or cone beam systems. The primary measure was the final scalar position of the SME (completely in scala tympani or not). Secondly, medial-lateral position and insertion depth were evaluated. RESULTS: Forty-four subjects received a CI532. The SME was located completely in scala tympani for all subjects. Pure round window (44% of the cases), extended round window (22%), and inferior and/or anterior cochleostomy (34%) approaches were successful across surgeons and cases. The SME was generally positioned close to the modiolus. Overinsertion of the array past the first marker tended to push the basal contacts towards the lateral wall and served only to increase the insertion depth of the first electrode contact without increasing the insertion depth of the most apical electrode. Complications were limited to tip fold-overs encountered in 2 subjects; both were attributed to surgical error, with both reimplanted successfully. CONCLUSIONS: The new Nucleus CI532 cochlear implant with SME achieved the design goal of producing little or no trauma as indicated by consistent scala tympani placement. Surgeons should be carefully trained to use the new deployment method such that tip fold-overs and over insertion may be avoided.

Speech-in-noise perception in unilateral hearing loss: Relation to pure-tone thresholds and brainstem plasticity.

We investigated speech recognition in noise in subjects with mild to profound levels of unilateral hearing loss. Thirty-five adults were evaluated using an adaptive signal-to-noise ratio (SNR50) sentence recognition threshold test in three spatial configurations. The results revealed a significant correlation between pure-tone average audiometric thresholds in the poorer ear and SNR thresholds in the two conditions where speech and noise were spatially separated: dichotic - with speech presented to the poorer ear and reverse dichotic - with speech presented to the better ear. This first result suggested that standard pure-tone air-conduction thresholds can be a reliable predictor of speech recognition in noise for binaural conditions. However, a subgroup of 14 subjects was found to have poorer-than-expected speech recognition scores, especially in the reverse dichotic listening condition. In this subgroup 9 subjects had been diagnosed with vestibular schwannoma at stage III or IV likely affecting the lower brainstem function. These subjects showed SNR thresholds in the reverse dichotic condition on average 4dB poorer (higher) than for the other 21 normally-performing subjects. For the 7 of 9 subjects whose vestibular schwannoma was removed, the deficit was no longer apparent on average 5 months following the surgical procedure. These results suggest that following unilateral hearing loss the capacity to use monaural spectral information is supported by the lower brainstem.

Cochlear implantation with the nucleus slim straight electrode in subjects with residual low-frequency hearing.

OBJECTIVES: To measure benefit in terms of speech recognition in quiet and in noise, and conservation of residual hearing in three groups of subjects implanted with the Nucleus Straight Research Array cochlear implant. This device incorporates the Nucleus Slim Straight electrode carrier designed to be easier to insert into the cochlea via the round window while potentially minimizing insertion trauma. DESIGN: The study was prospective, with sequential enrolment and within-subject repeated measures; 35 subjects were 15 to 84 years of age with varying levels of bilateral high-frequency HL. Subjects were divided into three groups (A, B, and C) according to preoperative air conduction hearing thresholds in the ear to implant at 500 Hz; A ≤ 50 (n = 11), 50 < B < 80 (n = 13), and C ≥ 80 (n = 11) dB HL. Speech recognition was assessed preoperatively and at intervals up to 1 year postimplantation. Hearing thresholds were monitored over time and CT scans were used to estimate electrode positions. RESULTS: Preoperative mean word recognition score was significantly greater for group A compared with group C in quiet (diff. 26.6%pts, p < 0.05), but not so in noise (diff. 7.9%pts, p = 0.72). However, a greater proportion of subjects in group A (81%) achieved a "worthwhile" gain in speech recognition score (>20%pts) in quiet compared with group C (63%). More importantly, for speech recognition in noise, all subjects in groups A and B achieved a >20%pts gain compared with only 73% in group C. Hearing in implanted ears was well conserved for low frequencies, both initially and up to 12 months postoperatively (15 dB median increase in thresholds 250 to 500 Hz). Only 3 of 35 (9%) cases lost all residual hearing in the implanted ear by 12 months. Where characteristic frequency corresponded to a position occupied by the electrode array, threshold increase was correlated with the preoperative hearing threshold (r = 0.7; p < 0.001) and closely approximated reported estimates of residual outer hair cell gain. For characteristic frequencies at positions apical to the electrode tip, the relation between threshold increase and residual hearing decreased in amplitude at 45 to 135 degrees (r = 0.42; p < 0.05), and disappeared at >135 degrees (r = 0.05; p > 0.05). CONCLUSION: Gains in speech recognition scores for subjects with better residual low-frequency hearing were greater or equal to those obtained by subjects with poorer residual hearing. Residual hearing after cochlear implantation with the Nucleus Slim Straight electrode array was well conserved across all three groups. It appears that the gain provided by outer hair cell function may be completely suppressed when an electrode array is in close proximity to the organ of Corti.

Partial deafness treatment with the nucleus straight research array cochlear implant.

INTRODUCTION: The Nucleus Straight Research Array (SRA) cochlear implant has a new 25-mm electrode carrier designed to minimize insertion trauma, in particular allowing easy insertion via the round window. The aims of this study were to measure preoperative to postoperative benefit in terms of speech recognition in quiet and in noise in three groups of patients (electrical complement, EC; electrical stimulation, ES; electro-acoustic stimulation, EAS) with varying levels of low-frequency hearing, and to evaluate the preservation of residual hearing after implantation with the SRA cochlear implant. METHODS: The study design was prospective with sequential enrolment and within-subject comparisons: 23 adult cochlear implant candidates were divided into three groups according to their level of preoperative residual hearing at 500 Hz (EC ≤50 dB; 50 dB < EAS < 80 dB; ES ≥80 dB). Monosyllabic word recognition using the SRA cochlear implant in combination with residual low-frequency hearing was assessed at 4 and 13 months after implantation. Hearing threshold levels were also monitored over time. RESULTS: Subjects across all three groups had significant improvements in speech recognition scores (i.e. >20 percentage points) both for listening in quiet (71% of subjects) and in noise (100% of subjects). The average score at 4 months after operation for words presented in quiet was 61.7%, and in 10 dB SNR noise 46.5%, compared to 34.4 and 10.6% preoperatively (p < 0.001). All subjects retained measurable hearing at 500 Hz in the implanted ear at 4 months after the operation; mean increases were 19, 29 and 1 dB for the EC, EAS and ES groups (n = 21). Across frequencies of 125-1000 Hz, the median increase in thresholds was 15 dB up to 13 months postoperatively (n = 15). CONCLUSIONS: Speech recognition performance of subjects with various levels of residual low-frequency hearing was significantly improved with the SRA cochlear implant. A high level and rate of hearing preservation was achieved with the SRA implanted using a round window surgical technique. Subjects with preoperative low-frequency hearing levels between 50 and 80 dB HL (EAS group) tended to lose more hearing than those with either better or worse hearing.

How much residual hearing is 'useful' for music perception with cochlear implants?

AIM: To compare performance on a song recognition task of bilaterally combined electric and acoustic hearing (bimodal stimulation) with electric or acoustic hearing alone. METHODS: Subjects were 14 adults with cochlear implants (CI) who continued to use a hearing aid (HA) in one/both ears. Subjects were asked to identify excerpts from 15 popular songs, which were familiar to them, presented in a random order via a single loudspeaker. Presentation conditions were fixed in order: bimodal, CI alone and then HA alone. Musical excerpts were presented in each condition with and then without lyrics. RESULTS: In a subgroup of subjects (n = 8) with better low-frequency residual hearing (thresholds <85 dB hearing level (HL)), mean scores for bimodal stimulation were significantly greater than for CI alone. In addition, mean 'no lyrics' scores for HA alone (59.7%) were significantly greater than for CI alone (38.8%). All of these subjects considered bimodal stimulation to be the most enjoyable way to listen to music. For the remaining subjects (n = 6) there was no benefit from using bimodal stimulation over CI alone, and the majority of these preferred to listen to music using CI alone. CONCLUSIONS: Bimodal stimulation provides better perception of popular music, particularly melody recognition, compared to CI alone when low-frequency residual hearing is better than 85 dB HL.

Combined electroacoustic stimulation in conventional candidates for cochlear implantation.

OBJECTIVE: To report on combined ipsilateral electrical and acoustic stimulation in a subset of conventional candidates for cochlear implantation where preoperative pure tone thresholds were 85-110 dB HL, 250-500 Hz). In the remaining 7 cases, residual hearing was maintained up to at least 6 months after operation with minor changes. Insertion depth angles in these cases ranged from 285 to 420 degrees . For these subjects, the mean preoperative score for words presented at 65 dB SPL was 22%. Mean postoperative scores were 56% for CI alone, and 68% for CI plus ipsilateral hearing aid (p < 0.05, paired t). For sentences presented in multitalker babble noise at 5 dB SNR, mean scores were 61% CI alone, and 75% CI+IpsiHA (p < 0.01, paired t). CONCLUSIONS: Hearing was conserved during surgery and over time in 70% of conventional candidates implanted with the Nucleus 24 Contour Advance CI who had significant levels of preoperative low-frequency residual hearing (

An investigation of input level range for the nucleus 24 cochlear implant system: speech perception performance, program preference, and loudness comfort ratings.

OBJECTIVE: Cochlear implant recipients often have limited access to lower level speech sounds. In this study we evaluated the effects of varying the input range characteristics of the Nucleus 24 cochlear implant system on recognition of vowels, consonants, and sentences in noise and on listening in everyday life. DESIGN: Twelve subjects participated in the study that was divided into two parts. In Part 1 subjects used speech processor (Nucleus 24 SPrint trade mark ) programs adjusted for three input sensitivity settings: a standard or default microphone sensitivity setting (MS 8), a setting that increased the input sensitivity by 10.5 dB (MS 15), and the same setting that increased input sensitivity but also incorporated the automatic sensitivity control (ASC; i.e., MS 15A) that is designed to reduce the loudness of noise. The default instantaneous input dynamic range (IIDR) of 30 dB was used in these programs (i.e., base level of 4; BL 4). Subjects were tested using each sensitivity program with vowels and consonants presented at very low to casual conversational levels of 40 dB SPL and 55 dB SPL, respectively. They were also tested with sentences presented at a raised level of 65 dB SPL in multi-talker babble at individually determined signal to noise ratios. In addition, subjects were given experience outside of the laboratory for several weeks. They were asked to complete a questionnaire where they compared the programs in different listening situations as well as the loudness of environmental sounds, and state the setting they preferred overall. In Part 2 of the study, subjects used two programs. The first program was their preferred sensitivity program from Part 1 that had an IIDR of 30 dB (BL 4). Seven subjects used MS 8 and four used MS 15, and one used the noise reduction program MS 15A. The second program used the same microphone sensitivity but had the IIDR extended by an additional 8 to 10 dB (BL 1/0). These two programs were evaluated similarly in the speech laboratory and with take-home experience as in Part 1. RESULTS PART 1: Increasing the microphone input sensitivity by 10.5 dB (from MS 8 to MS 15) significantly improved the perception of vowels and consonants at 40 and 55 dB SPL. The group mean improvement in vowel scores was 25 percentage points at 40 dB SPL and 4 percentage points at 55 dB SPL. The group mean improvement for consonants was 23 percentage points at 40 dB SPL and 11 percentage points at 55 dB SPL. Increased input sensitivity did not significantly reduce the perception of sentences presented at 65 dB SPL in babble despite the fact that speech peaks were then within the compressed range above the SPrint processor's automatic gain control (AGC) knee-point. Although there was a demonstrable advantage for perception of low-level speech with the higher input sensitivity (MS 15 and 15A), seven of the 12 subjects preferred MS 8, four preferred MS 15 or 15A, and one had no preference overall. Approximately half the subjects preferred MS 8 across the 18 listening situations, whereas an average of two subjects preferred MS 15 or 15A. The increased microphone sensitivity of MS 15 substantially increased the loudness of environmental sounds. However, use of the ASC noise reduction setting with MS 15 reduced the loudness of environmental sounds to equal or below that for MS 8. RESULTS PART 2: The increased instantaneous input range gave some improvement (8 to 9 percentage points for the 40 dB SPL presentation level) in the perception of consonants. There was no statistically significant increase in vowel scores. Mean scores for sentences presented at 65 dB SPL in babble were significantly lower (5 percentage points) for the increased IIDR setting. Subjects had no preference for the increased IIDR over the default. The IIDR setting had no effect on the loudness of environmental sounds. CONCLUSIONS: Given the fact that individuals differ in threshold (T) and comfort (C) levels for electrical stimulation, and preferred microphone sensitivity, volume control, and noise-reduction settings, it is essential for the clinicid recipient to determine what combination is best for the individual over several sessions. The results of this study clearly show the advantage of using higher microphone sensitivity settings than the default MS 8 to provide better speech recognition for low-level stimuli. However, it was also necessary to adjust other parameters such as map C levels, automatic sensitivity control and base level, to optimize loudness comfort in the diversity of listening situations an individual encounters in everyday life.

Adaptive dynamic range optimization for cochlear implants: a preliminary study.

OBJECTIVE: The present study investigated the acceptability and the effect of Adaptive dynamic range optimization (ADRO) on speech perception for cochlear implant subjects. ADRO is a preprocessing scheme that continuously adjusts the gain in each frequency band to optimize the signal in the output dynamic range. DESIGN: Speech processor programs were created with and without ADRO processing. Nine subjects were tested in the laboratory and encouraged to use both programs in everyday listening situations. Take-home experience was assessed with preference questionnaires. Speech perception performance was compared for the standard and ADRO programs using City University of New York (CUNY) sentences, consonant-nucleus-consonant (CNC) words, and closed set spondees presented in quiet. A range of presentation levels were used; from 70 to 40 dB sound pressure level (unweighted RMS). CUNY sentences were also presented in multi-talker babble with +15 dB and +10 dB signal to noise ratios. RESULTS: There was a significant improvement in speech perception scores with the ADRO programs compared with the standard. At 50 dB, the mean open set sentence scores in quiet improved by 16% (p < 0.001). There was an improvement in mean word score for CNC words presented at 60 dB of 9.5% (p < 0.001) and a 20% improvement in mean score for spondees presented at 40 dB. There was no significant difference in sentence scores between the ADRO and the standard program for sentences presented in either noise condition. ADRO was the preferred program in 59% of listening situations, with five out of nine subjects indicating a strong overall preference and three subjects indicating a slight preference for ADRO. CONCLUSIONS: Continual adjustment of channel gains using ADRO provided improved sound quality and improved speech perception performance. Therefore, ADRO is a viable alternative to fixed channel gain and offers a means for cochlear implantees to gain more benefit from their devices.