Factors affecting open-set word recognition in adults with cochlear implants.

OBJECTIVE: A great deal of variability exists in the speech-recognition abilities of postlingually deaf adult cochlear implant (CI) recipients. A number of previous studies have shown that duration of deafness is a primary factor affecting CI outcomes; however, there is little agreement regarding other factors that may affect performance. The objective of the present study was to determine the source of variability in CI outcomes by examining three main factors, biographic/audiologic information, electrode position within the cochlea, and cognitive abilities in a group of newly implanted CI recipients. DESIGN: Participants were 114 postlingually deaf adults with either the Cochlear or Advanced Bionics CI systems. Biographic/audiologic information, aided sentence-recognition scores, a high resolution temporal bone CT scan and cognitive measures were obtained before implantation. Monosyllabic word recognition scores were obtained during numerous test intervals from 2 weeks to 2 years after initial activation of the CI. Electrode position within the cochlea was determined by three-dimensional reconstruction of pre- and postimplant CT scans. Participants' word scores over 2 years were fit with a logistic curve to predict word score as a function of time and to highlight 4-word recognition metrics (CNC initial score, CNC final score, rise time to 90% of CNC final score, and CNC difference score). RESULTS: Participants were divided into six outcome groups based on the percentile ranking of their CNC final score, that is, participants in the bottom 10% were in group 1; those in the top 10% were in group 6. Across outcome groups, significant relationships from low to high performance were identified. Biographic/audiologic factors of age at implantation, duration of hearing loss, duration of hearing aid use, and duration of severe-to-profound hearing loss were significantly and inversely related to performance as were frequency modulated tone, sound-field threshold levels obtained with the CI. That is, the higher-performing outcome groups were younger in age at the time of implantation, had shorter duration of severe-to-profound hearing loss, and had lower CI sound-field threshold levels. Significant inverse relationships across outcome groups were also observed for electrode position, specifically the percentage of electrodes in scala vestibuli as opposed to scala tympani and depth of insertion of the electrode array. In addition, positioning of electrode arrays closer to the modiolar wall was positively correlated with outcome. Cognitive ability was significantly and positively related to outcome; however, age at implantation and cognition were highly correlated. After controlling for age, cognition was no longer a factor affecting outcomes. CONCLUSION: There are a number of factors that limit CI outcomes. They can act singularly or collectively to restrict an individual's performance and to varying degrees. The highest performing CI recipients are those with the least number of limiting factors. Knowledge of when and how these factors affect performance can favorably influence counseling, device fitting, and rehabilitation for individual patients and can contribute to improved device design and application.

Relation of electrically evoked compound action potential thresholds to behavioral T- and C-levels in children with cochlear implants.

OBJECTIVE: This study examined the relation of electrically evoked compound action potential thresholds obtained using neural response telemetry (NRT) to T- and C-levels in children's speech processor programs optimized for recognition of very soft to loud sounds while ensuring tolerance of very loud sounds. DESIGN: Forty-one children (age 2 to 14 yr) with stable electrical hearing participated. All children were Nucleus 24 System recipients and attended one of three auditory-oral schools that have on-site pediatric audiologists experienced at cochlear implant programming. Speech processor MAPs were created and adjusted over a period of months until aided warble-tone thresholds were between 10 and 30 dB HL at octave frequencies between 250 and 4000 Hz, and understanding of speech was maximized for many listening situations. At least 1 yr postactivation, visual (vNRT) and predicted (tNRT) thresholds were obtained on 9 to 11 electrodes and compared to each child's T- and C-level values on these electrodes in their MAPs. Test-retest stability of NRT thresholds was compared for two test sessions 1 mo apart. RESULTS: NRT-based evoked compound action potential thresholds could be obtained from 36 of the 41 children. vNRT and tNRT test-retest reliability was high; average correlation coefficients (r) across subjects were 0.90 (range: 0.64 to 0.99) and 0.88 (range: 0.31 to 1.00), respectively. Group average correlation coefficients between vNRT and T-level, vNRT and C-level, tNRT and T-level, and tNRT and C-level were low (0.18, 0.21, 0.24, and 0.26, respectively). Group mean tNRT thresholds were four current levels lower than the group mean vNRT thresholds. Subsequent analysis was performed with the vNRT thresholds because the range of test-retest correlation coefficients for individual subjects was narrower than with tNRT. Hierarchical linear modeling was used to determine if vNRT could be used to predict T- and C-levels. This analysis indicated a significant average relation between vNRT and T-levels and between vNRT and C-levels, but significant heterogeneity in the individual-level estimates of those relations. In other words, subjects varied significantly in the size of the relation between their individual vNRT values and both T- and C-levels. Attempts to account for that heterogeneity did not identify any subject characteristics that were significantly related to the individual-level parameters. CONCLUSIONS: The position of the group average vNRT and tNRT thresholds in the upper half of the dynamic range between Ts and Cs agrees with previous studies. The fact that the profile of vNRT thresholds did not parallel the profiles of Ts and Cs across electrodes for most children suggests that simply shifting the NRT profile to select T- and C-levels in initial MAPs is likely to result in a loudness imbalance for certain speech frequencies and/or tolerance issues for many children. This was verified by the hierarchical linear modeling analysis, which showed substantial and significant heterogeneity in the relations between vNRT and T-levels and between vNRT and C-levels. In summary, vNRT is not related to T- or C-levels in a simple and uniform way that would allow it to guide MAP fine tuning with any precision. Consequently, it is recommended that MAP fine tuning be based on the child's behavioral responses on individual electrodes.

The effect of instantaneous input dynamic range setting on the speech perception of children with the nucleus 24 implant.

OBJECTIVE: The purpose of this study was to examine the effects of a wider instantaneous input dynamic range (IIDR) setting on speech perception and comfort in quiet and noise for children wearing the Nucleus 24 implant system and the Freedom speech processor. In addition, children's ability to understand soft and conversational level speech in relation to aided sound-field thresholds was examined. DESIGN: Thirty children (age, 7 to 17 years) with the Nucleus 24 cochlear implant system and the Freedom speech processor with two different IIDR settings (30 versus 40 dB) were tested on the Consonant Nucleus Consonant (CNC) word test at 50 and 60 dB SPL, the Bamford-Kowal-Bench Speech in Noise Test, and a loudness rating task for four-talker speech noise. Aided thresholds for frequency-modulated tones, narrowband noise, and recorded Ling sounds were obtained with the two IIDRs and examined in relation to CNC scores at 50 dB SPL. Speech Intelligibility Indices were calculated using the long-term average speech spectrum of the CNC words at 50 dB SPL measured at each test site and aided thresholds. RESULTS: Group mean CNC scores at 50 dB SPL with the 40 IIDR were significantly higher (p < 0.001) than with the 30 IIDR. Group mean CNC scores at 60 dB SPL, loudness ratings, and the signal to noise ratios-50 for Bamford-Kowal-Bench Speech in Noise Test were not significantly different for the two IIDRs. Significantly improved aided thresholds at 250 to 6000 Hz as well as higher Speech Intelligibility Indices afforded improved audibility for speech presented at soft levels (50 dB SPL). CONCLUSION: These results indicate that an increased IIDR provides improved word recognition for soft levels of speech without compromising comfort of higher levels of speech sounds or sentence recognition in noise.

Recognition and localization of speech by adult cochlear implant recipients wearing a digital hearing aid in the nonimplanted ear (bimodal hearing).

BACKGROUND: The use of bilateral amplification is now common clinical practice for hearing aid users but not for cochlear implant recipients. In the past, most cochlear implant recipients were implanted in one ear and wore only a monaural cochlear implant processor. There has been recent interest in benefits arising from bilateral stimulation that may be present for cochlear implant recipients. One option for bilateral stimulation is the use of a cochlear implant in one ear and a hearing aid in the opposite nonimplanted ear (bimodal hearing). PURPOSE: This study evaluated the effect of wearing a cochlear implant in one ear and a digital hearing aid in the opposite ear on speech recognition and localization. RESEARCH DESIGN: A repeated-measures correlational study was completed. STUDY SAMPLE: Nineteen adult Cochlear Nucleus 24 implant recipients participated in the study. INTERVENTION: The participants were fit with a Widex Senso Vita 38 hearing aid to achieve maximum audibility and comfort within their dynamic range. DATA COLLECTION AND ANALYSIS: Soundfield thresholds, loudness growth, speech recognition, localization, and subjective questionnaires were obtained six-eight weeks after the hearing aid fitting. Testing was completed in three conditions: hearing aid only, cochlear implant only, and cochlear implant and hearing aid (bimodal). All tests were repeated four weeks after the first test session. Repeated-measures analysis of variance was used to analyze the data. Significant effects were further examined using pairwise comparison of means or in the case of continuous moderators, regression analyses. The speech-recognition and localization tasks were unique, in that a speech stimulus presented from a variety of roaming azimuths (140 degree loudspeaker array) was used. RESULTS: Performance in the bimodal condition was significantly better for speech recognition and localization compared to the cochlear implant-only and hearing aid-only conditions. Performance was also different between these conditions when the location (i.e., side of the loudspeaker array that presented the word) was analyzed. In the bimodal condition, the speech-recognition and localization tasks were equal regardless of which side of the loudspeaker array presented the word, while performance was significantly poorer for the monaural conditions (hearing aid only and cochlear implant only) when the words were presented on the side with no stimulation. Binaural loudness summation of 1-3 dB was seen in soundfield thresholds and loudness growth in the bimodal condition. Measures of the audibility of sound with the hearing aid, including unaided thresholds, soundfield thresholds, and the Speech Intelligibility Index, were significant moderators of speech recognition and localization. Based on the questionnaire responses, participants showed a strong preference for bimodal stimulation. CONCLUSIONS: These findings suggest that a well-fit digital hearing aid worn in conjunction with a cochlear implant is beneficial to speech recognition and localization. The dynamic test procedures used in this study illustrate the importance of bilateral hearing for locating, identifying, and switching attention between multiple speakers. It is recommended that unilateral cochlear implant recipients, with measurable unaided hearing thresholds, be fit with a hearing aid.

Use of computed tomography scans for cochlear implants.

While 3-dimensional (3D) imaging by computed tomography has long been desirable for research and treatment of cochlear-implant patients, technical challenges have limited its wide application. Recent developments in scanner hardware and image processing techniques now allow image quality improvements that make clinical applications feasible. Validation experiments were performed to characterize a new methodology and its imaging performance.

Effect of increased IIDR in the nucleus freedom cochlear implant system.

The objective of this study was to evaluate the effect of the increased instantaneous input dynamic range (IIDR) in the Nucleus Freedom cochlear implant (CI) system on recipients' ability to perceive soft speech and speech in noise. Ten adult Freedom CI recipients participated. Two maps differing in IIDR were placed on each subject's processor at initial activation. The IIDR was set to 30 dB for one map and 40 dB for the other. Subjects used both maps for at least one month prior to speech perception testing. Results revealed significantly higher scores for words (50 dB SPL), for sentences in background babble (65 dB SPL), and significantly lower sound field threshold levels with the 40 compared to the 30 dB IIDR map. Ceiling effects may have contributed to non-significant findings for sentences in quiet (50 dB SPL). The Freedom's increased IIDR allows better perception of soft speech and speech in noise.

Effect of frequency boundary assignment on speech recognition with the Nucleus 24 ACE speech coding strategy.

The choice of frequency boundaries for the analysis channels of cochlear implants has been shown to impact the speech perception performance of adult recipients (Skinner et al, 1995; Fourakis et al, 2004). While technological limitations heretofore have limited the clinical feasibility of investigating novel frequency assignments, the SPEAR3 research processor affords the opportunity to investigate an unlimited number of possibilities. Here, four different assignments are evaluated using a variety of speech stimuli. All participants accommodated to assignment changes, and no one assignment was significantly preferred. The results suggest that better performance can be achieved using a strategy whereby (1) there are at least 7-8 electrodes allocated below 1000 Hz, (2) the majority of remaining electrodes are allocated between 1100-3000 Hz, and (3) the region above 3 kHz is represented by relatively few electrodes (i.e., 1-3). The results suggest that such frequency assignment flexibility should be made clinically available.

In vivo estimates of the position of advanced bionics electrode arrays in the human cochlea.

OBJECTIVES: A new technique for determining the position of each electrode in the cochlea is described and applied to spiral computed tomography data from 15 patients implanted with Advanced Bionics HiFocus I, Ij, or Helix arrays. METHODS: ANALYZE imaging software was used to register 3-dimensional image volumes from patients' preoperative and postoperative scans and from a single body donor whose unimplanted ears were scanned clinically, with micro computed tomography and with orthogonal-plane fluorescence optical sectioning (OPFOS) microscopy. By use of this registration, we compared the atlas of OPFOS images of soft tissue within the body donor's cochlea with the bone and fluid/ tissue boundary available in patient scan data to choose the midmodiolar axis position and judge the electrode position in the scala tympani or scala vestibuli, including the distance to the medial and lateral scalar walls. The angular rotation 0 degrees start point is a line joining the midmodiolar axis and the middle of the cochlear canal entry from the vestibule. RESULTS: The group mean array insertion depth was 477 degrees (range, 286 degrees to 655 degrees). The word scores were negatively correlated (r = -0.59; p = .028) with the number of electrodes in the scala vestibuli. CONCLUSIONS: Although the individual variability in all measures was large, repeated patterns of suboptimal electrode placement were observed across subjects, underscoring the applicability of this technique.

Evaluation of equivalency in two recordings of monosyllabic words.

Thirty "new" lists of monosyllabic words were created at the University of Melbourne and recorded by Australian and American English speakers. These new lists and the ten original CNC lists (Peterson and Lehiste, 1962) were used during the feasibility study of the Nucleus Research Platform 8 Cochlear Implant System (Holden et al, 2004). Performance was similar across original and new lists for six implanted Australian subjects; for four implanted U.S. subjects, mean performance was 23 percentage points lower with the new than with the original lists. To evaluate differences between original and new lists for the American English recording, 22 CI recipients were administered all 40 CNC lists (30 new and 10 original lists). The overall mean word score for the new lists was significantly lower (22.3 percentage points) than for the original lists. Acoustic analysis revealed that decreased performance was most likely due to reduced amplitudes of certain initial and final consonants. The new CNC lists can be used as more difficult test material for clinical research.

Audibility and speech perception of children using wide dynamic range compression hearing AIDS.

PURPOSE: This study examined the relation of audibility for frequency-specific sounds and the Speech Intelligibility Index (SII) to speech perception abilities of children with sensorineural hearing loss using digital signal-processing hearing aids with wide dynamic range compression. METHOD: Twenty-six children age 5-15 years with pure-tone averages (0.5, 1.0, and 2.0 kHz) from 60-98 dB HL participated. Three subgroups were created based on the compression characteristics of each hearing aid. Minimum audibility was determined using aided thresholds for frequency-modulated tones and the SII calculated at 55 and 70 dB SPL using the simulated real-ear output of the hearing aid. The Lexical Neighborhood Test (LNT; K. I. Kirk, D. B. Pisoni, & M. J. Osberger, 1995) was presented at 50 and 70 dB SPL. RESULTS: LNT scores at 70 dB SPL were significantly higher than at 50 dB SPL. Average aided thresholds at 0.5, 1.0, and 2.0 kHz were negatively correlated with LNT scores at 50 dB SPL, and SIIs at 55 and 70 dB SPL were positively correlated with LNT scores at 50 and 70 dB SPL. CONCLUSIONS: Results support using aided thresholds and speech test scores at soft to loud levels as part of the amplification fitting process.

Speech recognition with the advanced combination encoder and transient emphasis spectral maxima strategies in nucleus 24 recipients.

One of the difficulties faced by cochlear implant (CI) recipients is perception of low-intensity speech cues. A. E. Vandali (2001) has developed the transient emphasis spectral maxima (TESM) strategy to amplify short-duration, low-level sounds. The aim of the present study was to determine whether speech scores would be significantly higher with TESM than with the advanced combination encoder (ACE) strategy fitted using procedures that optimize perception of soft speech and other sounds. Eight adult recipients of the Nucleus 24 CI system participated in this study. No significant differences in scores were seen between ACE and TESM for consonant-vowel nucleus-consonant (CNC) words presented at 55 and 65 dB SPL, for sentences in noise presented at 65 dB SPL at 2 different signal-to-noise ratios, or for closed-set vowels and consonants presented at 60 dB SPL. However, perception of stop consonants within CNC words presented at the lower level (55 dB SPL) was significantly higher with TESM than ACE. In addition, percentage of information transmitted for words at 55 dB SPL was significantly higher with TESM than with ACE for manner and voicing features for consonants in the initial word position. Analysis of closed-set consonants presented at 60 dB SPL revealed percentage of information transmitted for manner was significantly higher with TESM than with ACE. These improvements with TESM were small compared with those reported by Vandali for recipients of the Nucleus 22 CI system. It appears that mapping techniques used to program speech processors and improved processing capabilities of the Nucleus 24 system contributed to soft sounds being understood almost as well with ACE as with TESM. However, half of the participants preferred TESM to ACE for use in everyday life, and all but 1 used TESM in specific listening situations. Clinically, TESM may be useful to ensure the audibility of low-intensity, short-duration acoustic cues that are important for understanding speech, for recipients who are difficult to map, or if insufficient time precludes the use of mapping techniques to increase audibility of soft sound.

CT-derived estimation of cochlear morphology and electrode array position in relation to word recognition in Nucleus-22 recipients.

This study extended the findings of Ketten et al. [Ann. Otol. Rhinol. Laryngol. Suppl. 175:1-16 (1998)] by estimating the three-dimensional (3D) cochlear lengths, electrode array intracochlear insertion depths, and characteristic frequency ranges for 13 more Nucleus-22 implant recipients based on in vivo computed tomography (CT) scans. Array insertion depths were correlated with NU-6 word scores (obtained one year after SPEAK strategy use) by these patients and the 13 who used the SPEAK strategy from the Ketten et al. study. For these 26 patients, the range of cochlear lengths was 29.1-37.4 mm. Array insertion depth range was 11.9-25.9 mm, and array insertion depth estimated from the surgeon's report was 1.14 mm longer than CT-based estimates. Given the assumption that the human hearing range is fixed (20-20,000 Hz) regardless of cochlear length, characteristic frequencies at the most apical electrode (estimated with Greenwood's equation [Greenwood DD (1990) A cochlear frequency--position function of several species--29 years later. J Acoust. Soc. Am. 33: 1344-1356] and a patient-specific constant as) ranged from 308 to 3674 Hz. Patients' NU-6 word scores were significantly correlated with insertion depth as a percentage of total cochlear length (R = 0.452; r2 = 0.204; p = 0.020), suggesting that part of the variability in word recognition across implant recipients can be accounted for by the position of the electrode array in the cochlea. However, NU-6 scores ranged from 4% to 81% correct for patients with array insertion depths between 47% and 68% of total cochlear length. Lower scores appeared related to low spiral ganglion cell survival (e.g., lues), aberrant current paths that produced facial nerve stimulation by apical electrodes (i.e., otosclerosis), central auditory processing difficulty, below-average verbal abilities, and early Alzheimer's disease. Higher scores appeared related to patients' high-average to above-average verbal abilities. Because most patients' scores increased with SPEAK use, it is hypothesized that they accommodated to the shift in frequency of incoming sound to a higher pitch percept with the implant than would normally be perceived acoustically.

Blind deblurring of spiral CT images-comparative studies on edge-to-noise ratios.

A recently developed blind deblurring algorithm based on the edge-to-noise ratio has been applied to improve the quality of spiral CT images. Since the discrepancy measure used to quantify the edge and noise effects is not symmetric, there are several ways to formulate the edge-to-noise ratio. This article is to investigate the performance of those ratios with phantom and patient data. In the phantom study, it is shown that all the ratios share similar properties, validating the blind deblurring algorithm. The image fidelity improvement varies from 29% to 33% for different ratios, according to the root mean square error (RMSE) criterion; the optimal iteration number determined for each ratio varies from 25 to 35. Those ratios that are associated with most satisfactory performance are singled out for the image fidelity improvement of about 33% in the numerical simulation. After automatic blind deblurring with the selected ratios, the spatial resolution of CT is substantially refined in all the cases tested.

Blind deblurring of spiral CT images.

To discriminate fine anatomical features in the inner ear, it has been desirable that spiral computed tomography (CT) may perform beyond their current resolution limits with the aid of digital image processing techniques. In this paper, we develop a blind deblurring approach to enhance image resolution retrospectively without complete knowledge of the underlying point spread function (PSF). An oblique CT image can be approximated as the convolution of an isotropic Gaussian PSF and the actual cross section. Practically, the parameter of the PSF is often unavailable. Hence, estimation of the parameter for the underlying PSF is crucially important for blind image deblurring. Based on the iterative deblurring theory, we formulate an edge-to-noise ratio (ENR) to characterize the image quality change due to deblurring. Our blind deblurring algorithm estimates the parameter of the PSF by maximizing the ENR, and deblurs images. In the phantom studies, the blind deblurring algorithm reduces image blurring by about 24%, according to our blurring residual measure. Also, the blind deblurring algorithm works well in patient studies. After fully automatic blind deblurring, the conspicuity of the submillimeter features of the cochlea is substantially improved.

Optimizing cochlear implant speech performance.

Results of studies performed in our laboratory suggest that cochlear implant recipients understand speech best if the following speech processor parameters are individually chosen for each person: minimum and maximum stimulation levels on each electrode in the speech processor program (MAP), stimulation rate, and speech coding strategy. If these and related parameters are chosen to make soft sounds (from approximately 100 to 6,000 Hz) audible at as close to 20 dB hearing level as possible and loud sounds not too loud, recipients have the opportunity to hear speech in everyday life situations that are of key importance to children who are learning language and to all recipients in terms of ease of communication.

Effect of frequency boundary assignment on vowel recognition with the Nucleus 24 ACE speech coding strategy.

Two speech processor programs (MAPs) differing only in electrode frequency boundary assignments were created for each of eight Nucleus 24 Cochlear Implant recipients. The default MAPs used typical frequency boundaries, and the experimental MAPs reassigned one additional electrode to vowel formant regions. Four objective speech tests and a questionnaire were used to evaluate speech recognition with the two MAPs. Results for the closed-set vowel test and the formant discrimination test showed small but significant improvement in scores with the experimental MAP. Differences for the Consonant-Vowel Nucleus-Consonant word test and closed-set consonant test were nonsignificant. Feature analysis revealed no significant differences in information transmission. Seven of the eight subjects preferred the experimental MAP, reporting louder, crisper, and clearer sound. The results suggest that Nucleus 24 recipients should be given an opportunity to compare a MAP that assigns more electrodes in vowel formant regions with the default MAP to determine which provides the most benefit in everyday life.

Consensus panel on a cochlear coordinate system applicable in histologic, physiologic, and radiologic studies of the human cochlea.

HYPOTHESIS: An objective cochlear framework, for evaluation of the cochlear anatomy and description of the position of an implanted cochlear implant electrode, would allow the direct comparison of measures performed within the various subdisciplines involved in cochlear implant research. BACKGROUND: Research on the human cochlear anatomy in relation to tonotopy and cochlear implantation is conducted by specialists from numerous disciplines such as histologists, surgeons, physicists, engineers, audiologists, and radiologists. To allow accurate comparisons between and combinations of previous and forthcoming scientific and clinical studies, cochlear structures and electrode positions must be specified in a consistent manner. METHODS: Researchers with backgrounds in the various fields of inner ear research as well as representatives of the different manufacturers of cochlear implants (Advanced Bionics Corp., Med-El, Cochlear Corp.) were involved in consensus meetings held in Dallas, March 2005, and Asilomar, August 2005. Existing coordinate systems were evaluated, and requisites for an objective cochlear framework were discussed. RESULTS: The consensus panel agreed upon a 3-dimensional, cylindrical coordinate system of the cochlea using the "Cochlear View" as a basis and choosing a z axis through the modiolus. The zero reference angle was chosen at the center of the round window, which has a close relationship to the basal end of the Organ of Corti. CONCLUSION: Consensus was reached on an objective cochlear framework, allowing the outcomes of studies from different fields of research to be compared directly.

Speech recognition in cochlear implant recipients: comparison of standard HiRes and HiRes 120 sound processing.

OBJECTIVE: HiRes (HR) 120 is a sound-processing strategy purported to offer an increase in the precision of frequency-to-place mapping through the use of current steering. This within-subject study was designed to compare speech recognition as well as music and sound quality ratings for HR and HR 120 processing. SETTING: Cochlear implant/tertiary referral center. SUBJECTS: Eight postlinguistically deafened adults implanted with an Advanced Bionics CII or HR 90K cochlear implant. STUDY DESIGN/MAIN OUTCOME MEASURES: Performance with HR and HR 120 was assessed during 4 test sessions with a battery of measures including monosyllabic words, sentences in quiet and in noise, and ratings of sound quality and musical passages. RESULTS: Compared with HR, speech recognition results in adult cochlear implant recipients revealed small but significant improvements with HR 120 for single syllable words and for 2 of 3 sentence recognition measures in noise. Both easy and more difficult sentence material presented in quiet were not significantly different between strategies. Additionally, music quality ratings were significantly better for HR 120 than for HR, and 7 of 8 subjects preferred HR 120 over HR for listening in everyday life. CONCLUSION: HR 120 may offer equivalent or improved benefit to patients compared with HR. Differences in performance on test measures between strategies are dependent on speech recognition materials and listening conditions.

Restoring hearing symmetry with two cochlear implants or one cochlear implant and a contralateral hearing aid.

With today's technology and the demonstrated success of cochlear implantation, along with expanded candidacy criteria, the opportunity to provide optimal hearing to both ears for individuals with severe-to-profound hearing loss is greater than ever. This article reviews the advantages of binaural hearing and the disadvantages of hearing with only one ear or hearing with two ears with significantly different sound thresholds. A case study is presented that demonstrates the benefit of bimodal hearing (i.e., a cochlear implant [CI] in one ear and a contralateral hearing aid [HA]) in a nontraditional CI candidate with asymmetrical hearing thresholds. Then, selected studies in adult recipients who use a CI and contralateral HA or who use two CIs are summarized. The data overall demonstrate that bilateral CI recipients, traditional bimodal recipients, and nontraditional bimodal recipients experience substantial binaural hearing advantages, including improved speech recognition in noise, localization, and functional everyday communication. These results indicate that bilateral stimulation of the auditory system through a CI and contralateral HA or two CIs is beneficial and should become standard clinical practice.

Role of electrode placement as a contributor to variability in cochlear implant outcomes.

HYPOTHESIS: Suboptimal cochlear implant (CI) electrode array placement may reduce presentation of coded information to the central nervous system and, consequently, limit speech recognition. BACKGROUND: Generally, mean speech reception scores for CI recipients are similar across different CI systems, yet large outcome variation is observed among recipients implanted with the same device. These observations suggest significant recipient-dependent factors influence speech reception performance. This study examines electrode array insertion depth and scalar placement as recipient-dependent factors affecting outcome. METHODS: Scalar location and depth of insertion of intracochlear electrodes were measured in 14 patients implanted with Advanced Bionics electrode arrays and whose word recognition scores varied broadly. Electrode position was measured using computed tomographic images of the cochlea and correlated with stable monosyllabic word recognition scores. RESULTS: Electrode placement, primarily in terms of depth of insertion and scala tympani versus scala vestibuli location, varies widely across subjects. Lower outcome scores are associated with greater insertion depth and greater number of contacts being located in scala vestibuli. Three patterns of scalar placement are observed suggesting variability in insertion dynamics arising from surgical technique. CONCLUSION: A significant portion of variability in word recognition scores across a broad range of performance levels of CI subjects is explained by variability in scalar location and insertion depth of the electrode array. We suggest that this variability in electrode placement can be reduced and average speech reception improved by better selection of cochleostomy sites, revised insertion approaches, and control of insertion depth during surgical placement of the array.