Otology & Neurotology 36:430Y436 Ó 2015, Otology & Neurotology, Inc.
The Impact of Cochlear Implantation on Speech Understanding, Subjective Hearing Performance, and Tinnitus Perception in Patients with Unilateral Severe to Profound Hearing Loss *†‡Dayse Ta´vora-Vieira, *§Roberta Marino, †Aanand Acharya, and *†‡Gunesh P. Rajan *Otolaryngology, Head and Neck Surgery, School of Surgery, University of Western Australia, Perth; ÞFremantle Hospital Campus, Fremantle; þFiona Stanley Hospital, Perth; and §Specialist Hearing Services, Wembley, Australia
Results: Twenty-eight postlingual unilaterally deaf adults with or without tinnitus were implanted. There was a significant improvement in speech perception in noise across time in all spatial configurations. There was an overall significant improvement on the subjective perception of hearing and quality of life. Tinnitus disturbance reduced significantly across time. Age at implantation and duration of deafness did not influence the outcomes significantly. Conclusion: Cochlear implantation provided significant improvement in speech understanding in challenging situations, subjective perception of hearing performance, and quality of life. Cochlear implantation also resulted in reduced tinnitus disturbance. Age at implantation and duration of deafness did not seem to influence the outcomes. Key Words: Age at implantationVCochlear implantVDuration of deafnessVSpeech perception in noiseVTinnitus suppressionVUnilateral deafness.
Objectives: This study aimed to determine the impact of cochlear implantation on speech understanding in noise, subjective perception of hearing, and tinnitus perception of adult patients with unilateral severe to profound hearing loss and to investigate whether duration of deafness and age at implantation would influence the outcomes. In addition, this article describes the auditory training protocol used for unilaterally deaf patients. Design: This is a prospective study of subjects undergoing cochlear implantation for unilateral deafness with or without associated tinnitus. Methods: Speech perception in noise was tested using the Bamford-Kowal-Bench speech-in-noise test presented at 65 dB SPL. The Speech, Spatial, and Qualities of Hearing Scale and the Abbreviated Profile of Hearing Aid Benefit were used to evaluate the subjective perception of hearing with a cochlear implant and quality of life. Tinnitus disturbance was measured using the Tinnitus Reaction Questionnaire. Data were collected before cochlear implantation and 3, 6, 12, and 24 months after implantation.
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The use of cochlear implantation in subjects with unilateral deafness (UD) was first reported in the literature in 2008 (1). Although that study was designed to investigate the benefits of cochlear implantation for tinnitus inhibition, it was found that speech perception in noise scores were also enhanced (2). Since then, several other studies have investigated the benefits of cochlear implantation in subjects with UD. Buechner et al. (3) reported that the cochlear implant (CI) decreased tinnitus annoyance and improved speech understanding in some of the subjects. Arndt et al. (4) conducted a study to
compare the outcomes of the available treatment options for UD and found that CI users demonstrated significant improvement in localization and speech understanding. Other authors have reported similar positive hearing benefits from CI use in small cohorts of patients with UD (5Y7). The main disabilities that affect adults with UD are lack of spatial hearing, impaired speech intelligibility in the presence of background noise (BN), and reduced speech understanding when speech is presented to the impaired ear (8). In a study by Priwin et al. (9), 14% of the subjects with unilateral hearing loss had severe difficulty in a group conversation, 19% found that the ability to converse in the presence of traffic noise was severely affected and even conversation in quiet was difficult for 26% of the participants. Vicci de Araujo et al. (10) showed that 73% of patients with unilateral hearing loss reported some
Address correspondence and reprint requests to Dayse Ta´vora-Vieira, Au.D., Fremantle Hospital Campus, Fremantle, Western Australia, Australia; E-mail: [email protected] The authors disclose no conflicts of interest. Supplemental digital content is available in the text.
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UNILATERAL DEAFNESS COCHLEAR IMPLANTATION level of handicap, 52% reported difficulty at the cinema, and 40% reported difficulty on the telephone. Subjects with UD are deprived of binaural hearing, which is the ability of the auditory system to process and integrate inputs from both ears. Binaural hearing is essential for spatial hearing, and it improves speech perception in noise (11Y14). The benefits of binaural hearing through bimodal amplification and bilateral CIs in adults have been well documented (15Y18). Therefore, it might be expected that patients with UD would attain additional benefit from adding a CI to their unilaterally deafened ear to be used together with their contralateral normal-hearing ear. However, to the best of our knowledge, there is no literature reporting the selection criteria and the key factors that might influence the outcomes. This study was designed to investigate whether duration of deafness or age at implantation has any impact on the outcomes. We hypothesized that, in subjects with postlingual UD, duration of deafness and age at implantation would not play a major role on the outcomes of cochlear implantation. Duration of deafness has been used on studies with bilateral severe-to-profound hearing loss as a predictive factor for the outcomes of cochlear implantation in postlingually deaf patients (19,20). However, recent investigation has shown that this is particularly true if analyzing the duration of deafness in the better hearing ear (21). It seems that, if the contralateral ear has good speech understanding, good outcomes of implantation are obtained from the ear with a long duration of deafness (21). Thus, subjects with long-term UD should not be denied a CI based solely on this criterion. Age at implantation is well accepted as another key factor that will determine the outcomes of CI in congenital bilateral deafness (22,23). In the contrary, it seems that this is not a determinant factor for CI in adults with postlingual deafness (24,25). The preliminary results of our first nine patients, with a follow-up of 3 months after cochlear implantation, have been previously published (26). This study adds to the existing literature by incorporating a larger number of subjects and investigating 1) the impact of CI use in speech intelligibility in noise, 2) the long-term impact of CI use on the subjective perception of hearing, 3) if use of the CI decreases tinnitus perception in the long-term, and 4) if duration of deafness and age at implantation affect the outcomes. MATERIALS AND METHODS This study was designed and conducted in accordance with the Declaration of Helsinki. Ethics approval was obtained from the relevant ethics and institutional review committees. Twenty-eight adult subjects (15 women and 13 men) with unilateral sensorineural severe-to-profound hearing loss were enrolled in this study. Thirteen patients had tinnitus. The better-hearing ear had a pure-tone average (PTA0.5Y4kHz) of 30 dB or less. Table 1 shows the subjects’ detailed demographic data. All subjects were implanted with a 31.5- or 28-mm electrode array (MED-EL GmbH, Innsbruck, Austria). The surgical procedure used was a hearing preservation technique, as described by Rajan et al. (27).
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Standardized preoperative evaluation of the subjects included high-resolution computed tomography and magnetic resonance imaging of the temporal bones and brain to rule out the presence of any inner ear anomalies or cochlear nerve pathologies that might constrain electrical stimulation by a CI. Audiologic workup included immittance measures, audiometry, and speech discrimination in quiet using the Arthur Boothroyd word list (28). A hearing aid was fitted to the poorer ear if any functional hearing was present and, if this was unsuccessful, a patient was considered for a CI. To participate in the study, all subjects were asked to trial a conventional contralateral routing of signal (CROS) hearing aid and the bone-anchored hearing aid (BAHA) mounted on a soft band. They used the device for 2 weeks each. This trial aimed to give the subjects the option to experience a noninvasive or less invasive rehabilitation option for UD. Speech perception testing was performed using the adaptive Bamford-Kowal-Bench speech-in-noise (BKB-SIN) test (29), which investigates the signal-to-noise ratio needed to achieve a score of 50% of the words correct. Tests were performed in a free field, with the subject seated 1 m away from loudspeakers located at angles of 0, j90, and +90 degrees. The spatial configurations used for speech testing were S0/N0, speech and noise presented from the front; S0/NHE, speech presented from the front and noise to the normal-hearing ear; and SCI/NHE, speech presented to the implanted ear and noise to the side of the normal-hearing ear. The spatial configuration SCI/NHE was chosen on the basis of being the most challenging situation as clinically described by the patients. Subjective assessment of hearing was determined using the standardized Speech, Spatial and Qualities of Hearing (SSQ) questionnaire (30). The SSQ is composed of 50 questions, and each question has a score of 0 to 10. A higher score on the SSQ indicates better subjective perception of hearing speech, spatial orientation, and quality of hearing. All subjects were asked to complete the SSQ presurgically and at 3, 6, and 12 months after cochlear implantation. The long-term benefit was verified at 24 months. The Abbreviated Profile of Hearing Aid Benefit (APHAB) is a self-assessment tool composed of 24 questions that indicate the level of difficulty a person with hearing loss faces in various everyday listening situations. It aims to calculate the benefit of amplification as perceived by the subject by comparing the subjects’ reported difficulty in unaided and aided conditions. High scores mean that the patients experience performance difficulties more often. The questionnaire has four subscales, ease of communication (EC), reverberation (RV), BN, and aversiveness, and one global scale (31). Although the APHAB is a validated questionnaire for hearing aid users, it was thought that at least three of the subscales such as EC, RV, and BN, together with the global scale, would provide more information on how the subjects rated their hearing with a CI. The APHAB was completed presurgically and at 12 months after cochlear implantation to determine the subjective benefit of CI use. Tinnitus disturbance was assessed using the Tinnitus Reaction Questionnaire (TRQ [32]). The TRQ is composed of 26 questions designed to establish the effects of tinnitus during the past week on lifestyle and general well-being using a scale from 0 (not at all) to 4 (almost all of the time). The final totaled score can range from 0 through 104. All subjects were asked to complete the TRQ presurgically and at 3, 6, and 12 months after CI activation. Long-term effect was also measured at 24 months.
Auditory Training Intensive auditory training was provided for all participants. The rehabilitation methods were discussed at length with each Otology & Neurotology, Vol. 36, No. 3, 2015
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TABLE 1. Subject
Duration of Age at Sex deafness (yr) implantation (yr) Ear
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
M M F M M M M M F F F M F M F F F M M F F M F F M F F F
3 2 40 0.6 33 35 2 20 6 0.6 20 1 0.6 39 27 0.3 12 0.3 0.4 1.5 1 5 4 2.5 7 1 0.9 1.5
45 56 55 70 55 68 38 40 46 38 55 60 53 51 48 39 41 62 72 73 57 71 39 74 53 57 42 47
R L L R L R R R R R L L R R R R L R L L L R R L R L L R
Subject demographic data Pure-tone average (0.5Y4 kHz)- Pure-tone average (0.5Y4 kHz)nonimplanted ear in dBa implanted ear in dBa
Etiology ISSNHL Posttraumatic Unknown ISSNHL Unknown Iatrogenic Posttraumatic Posttraumatic ISSNHL ISSNHL Me´nie`re’s disease Unknown ISSNHL Mumps Ototoxicity Fistula Unknown ISSNHL ISSNHL Unknown ISSNHL Unknown Unknown Unknown Unknown ISSNHL ISSNHL ISSNHL
10 18 13 25 19 27 3 34 32 24 18 18 13 4 13 27 5 7 24 21 25 30 19 21 24 32 10 21
74 90 79 84 97 9110 9110 9110 95 93 9110 97 75 9110 75 9110 72 72 82 9110 76 74 9110 9110 95 80 92 87
F indicates female; ISSNHL, idiopathic sudden sensorineural hearing loss; L, Left; M, male; R, Right. a Before cochlear implantation.
individual before his or her enrollment in the study to ensure the participant’s compliance and strong commitment to the training. Participants agreed to commit 30 to 60 minutes per day to auditory training. Auditory training started at Week 2 or 3 after CI activation. Patients were seen, on average, weekly for the first 6 weeks and then monthly up to 6 months after CI activation. All subjects were provided with an audio cable that connected the speech processor to an audio source. A map for direct audio input connection was created for each subject at Week 2 or 3, depending on the individual’s tolerance to electrical stimulation. To establish the most comfortable levels of the direct audio input map, a series of progressive maps were created. The speech processor was then connected to an audio player, and the subject was asked to listen to a speech signal and select the map that best matched the most comfortable level while using the audio cable. The subjects were then provided with prerecorded material composed of meaningful English wordsVfor example, numbers, colors, animals, fruits. When the subjects were able to discriminate the words, a list of prerecorded meaningful sentences was provided. The next step was to listen to audiobooks. The audiobooks varied in vocabulary difficulty, sentence length, and reading speed rate. Those with greater difficulties were provided with books that encompassed a simple vocabulary, known themes, and a low reading speed (as low as 40 words per minute). As their speech discrimination improved, subjects progressed onto audiobooks with a more complex vocabulary and a higher reading speed rate. Visual cues were permitted at the beginning of the program and removed as the subjects progressed. To ensure that all subjects received similar auditory training, a computer was available at the implant center for those who did not have access to a computer or CD player at home.
Statistical Analyses Three-way repeated-measures analysis of variance was used to determine the effect of time, age at implantation, and duration of deafness, as well as their interaction on the three spatial setups of the adaptive BKB-SIN test, the three SSQ subscales, and the TRQ scores. For the APHAB subscales and the AHPAB global scale, a paired-sample t test was used to examine a significant difference between preoperative testing and 12-month postoperative testing. To test a possible influence of age and duration of deafness as well as their interaction at the single tested intervals, a multivariate general linear model was performed for all outcome variables. All p values are results of two-sided tests. A value of p G 0.05 was considered to indicate statistical significance.
RESULTS Speech Perception in Noise The speech perception results in noise of the adaptive BKB-SIN test in the three spatial setups are shown in Figure 1. Mean scores for the S0/N0 spatial test setup ranged from 4.47 (TSD, 1.796) preoperatively to 1.90 (TSD, 1.917) 12 months postoperatively. Mean scores for the S0/NHE spatial test setup ranged from 0.14 (TSD, 3.681) preoperatively to j1.57 (TSD, 3.217) 12 months postoperatively. Mean scores for the SCI/NHE spatial test setup ranged from 5.11 (TSD, 3.722) preoperatively to j0.80 (TSD, 3.262) 12 months postoperatively. Time (preoperatively and 3, 6, and 12 months postoperatively) had a significant main effect on the S0/N0 spatial test outcome (F3,42 = 21.878; p G 0.001), on the
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FIG. 1. The Bamford-Kowal-Bench speech-in-noise test results across time. Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers.
S0/NHE spatial test outcome (F3,42 = 7.226; p = 0.003), and on the SCI/NHE spatial test outcome (F3,42 = 74.326; p G 0.001). There was no significant interaction between age at implantation and duration of deafness across time or any of their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (see Supplemental Digital Contents 1, 2, and 3, http://links.lww.com/MAO/A274, which show the p values for the three spatial configuration). Subjective Testing The results of the three subscales of the SSQ are shown in Figure 2. Mean scores for the subscale Speech ranged from 4.69 (TSD, 1.827) preoperatively to 7.65 (TSD, 1.105) 24 months postoperatively. Mean scores for the subscale Spatial ranged from 2.61 (TSD, 1.604) preoperatively to 7.37 (TSD, 1.204) 24 months postoperatively. Mean scores for the subscale Quality of Hearing ranged from 6.16 (TSD, 1.797) preoperatively to 8.15 (TSD, 0.947) 24 months postoperatively. Time had a significant main effect on the Speech subscale (F1.4,12.7 = 6.051; p = 0.021), on the Spatial subscale (F1.6,14.7 = 24.160; p G 0.001), and on the Quality of Hearing subscale (F1.5,13.3 = 6.326; p = 0.017). There was no significant interaction between age at implantation and duration of deafness across time or any of
their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (see Supplemental Digital Content 4, 5, and 6, http://links.lww.com/MAO/A274, which show the p values for the three SSQ subscales). The results of the 3 APHAB subscales are shown in Figure 3. Mean scores on the EC subscale were 33.6 (TSD, 14.912) at preoperative testing and 14.4 (TSD, 12.602) at 12 months postoperatively. Mean scores on the subscale RV were 46.6 (TSD, 17.570) at preoperative testing and 23.2 (TSD, 12.984) 12 months postoperatively. Mean scores on the BN subscale were 63.6 (TSD, 14.212) at preoperative testing and 32.1 (TSD, 12.576) at 12 months postoperatively. Mean scores on the global scale were 47.2 (TSD, 13.797) at preoperative testing and 22.9 (TSD, 11.802) 12 months postoperatively. The subjective perception of EC improved significantly between preoperative testing and 12 months postoperatively (t = 4.97; p G 0.001). The subjective perception of RV improved significantly between preoperative testing and 12 months postoperatively (t = 5.38; p G 0.001). The subjective perception of BN improved significantly between preoperative testing and 12 months postoperatively (t = 6.45; p G 0.001). There was no significant interaction between age at implantation and duration of deafness preoperatively or 12 months postoperatively or any of their
FIG. 2. Speech, Spatial, and Qualities of hearing subscale results across time. Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers. Otology & Neurotology, Vol. 36, No. 3, 2015
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FIG. 3. The Abbreviated Profile of Hearing Aid Benefit subscale and global scale results between preoperative testing and 12-month postoperative testing (percentage). Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers.
possible interactions preoperatively or 12 months postoperatively (p = 0.090Yp = 0.968; see Supplemental Digital Content 7, 8, and 9, http://links.lww.com/MAO/A274, which show the p values for the three APHAB subscales). The global scale improved significantly between preoperative testing and 12 months postoperatively (t = 6.15; p G 0.001). There was no significant interaction between age at implantation and duration of deafness preoperatively or 12 months postoperatively or any of their possible interactions preoperatively or 12 months postoperatively (p = 0.122Yp = 0.543; see Supplemental Digital Content 10, http://links.lww.com/MAO/A274, which shows the p values for the APHAB global scale). Tinnitus Disturbance The results of the TRQ are shown in Figure 4. Mean scores for the TRQ were 48.8 (TSD, 27.150) at preoperative testing and 1.75 (TSD, 4.200) 24 months postoperatively. Time had a significant main effect on the TRQ (F1.3,7.8 = 10.098; p = 0.011). There was no significant interaction between age at implantation and duration of deafness across time or any of their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (p = 0.170Yp = 1.000; see Supplemental Digital Content 11,
FIG. 4.
http://links.lww.com/MAO/A274, which shows the p values for the TRQ scores). DISCUSSION Recent literature has demonstrated cochlear implantation to be a suitable hearing rehabilitation option for adults with unilateral profound deafness. A CI is the only option that provides ear-specific information and thus potentially the benefits of binaural hearing. There are known benefits to listening with two ears, as reviewed in the International Consensus on Bilateral Cochlear Implants, which suggested that speech recognition in noise is better under binaural listening conditions than under binaural deprivation (33). Litovsky et al. (34) have shown that, by using bilateral implants, a 12% to 33% improvement in speech perception can be achieved by deaf adults. Bilaterally implanted deaf children perform better than children with a unilateral CI in speech in noise testing (35). However, the benefits of CIs in UD and the improvement on speech performance in noise have been addressed by very few groups during the past few years (3Y7). To date, the selection criteria for cochlear implantation in UD are not clearly established and factors that might determine the outcomes are unknown. This study addressed this issue by analyzing the potential influence that age at implantation and duration of deafness might have on the CI outcomes.
Tinnitus Reaction Questionnaire results across time. Median values are displayed as a horizontal line, mean values as black squares.
Otology & Neurotology, Vol. 36, No. 3, 2015
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UNILATERAL DEAFNESS COCHLEAR IMPLANTATION This study investigated the hearing benefits of CI in terms of speech perception, self-assessment of hearing performance, and tinnitus disturbance in a cohort larger than 25 subjects with long-term follow-up. It is the first to investigate whether duration of deafness and age at implantation have an effect on the outcomes. Our results showed a significant improvement in speech perception in noise scores when speech and noise are presented from the front (S0/N0) and when speech is presented from the front (S0/NHE) or from the CI side (SCI/NHE) with the noise presented to the normal-hearing ear. These results indicate that patients with UD may be able to make use of some of the benefits associated with binaural hearing. Both SSQ and APHAB showed a significant subjective improvement of hearing with CI use. The analysis of the SSQ scores confirmed that the improvement over time was significant for all 3 subscales: speech, spatial hearing and qualities of hearing. Similarly, Arndt et al. (4) reported a significant improvement in the speech and spatial hearing subscales while Vermeire and Van de Heyning (2) found an improvement in all three subscales, indicating that the subjective perception of hearing improves with CI use in UD subjects. The SSQ questionnaire was repeated at 24 months post-CI, and the scores showed that the subjective benefit remained stable in the long-term. The results of the APHAB were in line with the SSQ scores, with an improvement in the subscales ease of hearing, RV, and BN. The scores of the aversiveness subscale did not change significantly before and after surgery. This demonstrates that CI in UD enhances patients’ selfperception of hearing performance and does not create any tolerance issues. The disturbance caused by tinnitus also decreased for the subjects. A further follow-up at 24 months showed that the improvement was stable in the long-term. A significant positive effect on tinnitus has been reported previously (1,3,36). In accordance with the data herein, Punte et al. (37) reported a significant decrease in tinnitus distress in 26 subjects who received a CI for UD associated with tinnitus. Thus, it seems that CI can be used as an effective means of reducing tinnitus disturbance. Our results showed that age at implantation or duration of deafness did not have a significant effect on the speech perception in noise scores, subjective hearing performance as measured by the SSQ and APHAB, and on the improvement of tinnitus, confirming our initial hypothesis that these factors would not play a key role in the rehabilitation of postlingual UD using CI. There was a concern that subjects with normal contralateral hearing would have difficulties integrating the acoustic and electric signals. In contrast to standard CI recipients who had to rely on some kind of amplification, subjects with UD might be expected to give up using their CI if their progress was too slow or if the obvious benefits did not overcome the challenges associated with CI use. Studies have demonstrated the benefits of active auditory training for patients using auditory rehabilitation (38,39). In an earlier UD case study by Nawaz et al. (40), one subject received training to stimulate both ears simulta-
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neously and promote binaural integration with success. In our study, intensive auditory training was provided that aimed to facilitate acclimatization to the CI. Further investigation is necessary to establish the exact contribution of auditory training. Cumulatively, these results, along with device acceptance, suggest that subjects with UD are probably able to combine the acoustic and electrical signals. CONCLUSION The results of the present study indicate that, in subjects with UD, speech perception in noise is improved with CI use. CI use improves the subjective perception of hearing in UD subjects and decreases the disturbance of tinnitus, which may in turn contribute to an overall positive subjective impression of benefits in this group of subjects. It seems that age at implantation and duration of deafness do not affect the outcome. Acknowledgments: The authors thank E. A. for statistical analyses and I. G. A. and U. D. for editing a version of this article.
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27. Rajan GP, Kuthubutheen J, Hedne N, et al. The role of preoperative, intratympanic glucocorticoids for hearing preservation in cochlear implantation: a prospective clinical study. Laryngoscope 2012;122:190Y5. 28. Boothroyd A. Developments in speech audiometry. Sound 1968; 2:3Y10. 29. Bench J, Kowal A, Bamford J. The BKB (Bamford-Kowal-Bench) sentence lists for partially-hearing children. Br J Audiol 1979; 13:108Y12. 30. Gatehouse S, Noble W. The Speech, Spatial and Qualities of Hearing Scale (SSQ). Int J Audiol 2004;43:85Y99. 31. Cox RM, Alexander GC. The Abbreviated Profile of Hearing Aid Benefit. Ear Hear 1995;16:176Y86. 32. Wilson PH, Henry J, Bowen M, et al. Tinnitus reaction questionnaire: psychometric properties of a measure of distress associated with tinnitus. J Speech Hear Res 1991;34:197Y201. 33. Offeciers E, Morera C, Muller J, et al. International consensus on bilateral cochlear implants and bimodal stimulation. Acta Otolaryngol 2005;125:918Y9. 34. Litovsky R, Parkinson A, Arcaroli J, et al. Simultaneous bilateral cochlear implantation in adults: a multicenter clinical study. Ear Hear 2006;27:714Y31. 35. Kuhn-Inacker H, Shehata-Dieler W, Muller J, et al. Bilateral cochlear implants: a way to optimize auditory perception abilities in deaf children? Int J Pediatr Otorhinolaryngol 2004;68:1257Y66. 36. Ramos A, Polo R, Masgoret E, et al. Cochlear implant in patients with sudden unilateral sensorineural hearing loss and associated tinnitus. Acta Otorrinolaringol Esp 2012;63:15Y20. 37. Punte AK, Vermeire K, Hofkens A, et al. Cochlear implantation as a durable tinnitus treatment in single-sided deafness. Cochlear Implants Int 2011;12:S26Y9. 38. Fu QJ, Galvin JJ. Perceptual learning and auditory training in cochlear implant recipients. Trends Amplif 2007;11:193. 39. Fu QJ, Galvin J, Wang X, et al. Effects of auditory training on adult cochlear implant patients: a preliminary report. Cochlear Implants Int 2004;5:84Y90. 40. Nawaz S, McNeill C, Greenberg SL. Improving sound localization after cochlear implantation and auditory training for the management of single-sided deafness. Otol Neurotol 2014;35:271Y6.
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The Impact of Cochlear Implantation on Speech Understanding, Subjective Hearing Performance, and Tinnitus Perception in Patients with Unilateral Severe to Profound Hearing Loss *†‡Dayse Ta´vora-Vieira, *§Roberta Marino, †Aanand Acharya, and *†‡Gunesh P. Rajan *Otolaryngology, Head and Neck Surgery, School of Surgery, University of Western Australia, Perth; ÞFremantle Hospital Campus, Fremantle; þFiona Stanley Hospital, Perth; and §Specialist Hearing Services, Wembley, Australia
Results: Twenty-eight postlingual unilaterally deaf adults with or without tinnitus were implanted. There was a significant improvement in speech perception in noise across time in all spatial configurations. There was an overall significant improvement on the subjective perception of hearing and quality of life. Tinnitus disturbance reduced significantly across time. Age at implantation and duration of deafness did not influence the outcomes significantly. Conclusion: Cochlear implantation provided significant improvement in speech understanding in challenging situations, subjective perception of hearing performance, and quality of life. Cochlear implantation also resulted in reduced tinnitus disturbance. Age at implantation and duration of deafness did not seem to influence the outcomes. Key Words: Age at implantationVCochlear implantVDuration of deafnessVSpeech perception in noiseVTinnitus suppressionVUnilateral deafness.
Objectives: This study aimed to determine the impact of cochlear implantation on speech understanding in noise, subjective perception of hearing, and tinnitus perception of adult patients with unilateral severe to profound hearing loss and to investigate whether duration of deafness and age at implantation would influence the outcomes. In addition, this article describes the auditory training protocol used for unilaterally deaf patients. Design: This is a prospective study of subjects undergoing cochlear implantation for unilateral deafness with or without associated tinnitus. Methods: Speech perception in noise was tested using the Bamford-Kowal-Bench speech-in-noise test presented at 65 dB SPL. The Speech, Spatial, and Qualities of Hearing Scale and the Abbreviated Profile of Hearing Aid Benefit were used to evaluate the subjective perception of hearing with a cochlear implant and quality of life. Tinnitus disturbance was measured using the Tinnitus Reaction Questionnaire. Data were collected before cochlear implantation and 3, 6, 12, and 24 months after implantation.
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The use of cochlear implantation in subjects with unilateral deafness (UD) was first reported in the literature in 2008 (1). Although that study was designed to investigate the benefits of cochlear implantation for tinnitus inhibition, it was found that speech perception in noise scores were also enhanced (2). Since then, several other studies have investigated the benefits of cochlear implantation in subjects with UD. Buechner et al. (3) reported that the cochlear implant (CI) decreased tinnitus annoyance and improved speech understanding in some of the subjects. Arndt et al. (4) conducted a study to
compare the outcomes of the available treatment options for UD and found that CI users demonstrated significant improvement in localization and speech understanding. Other authors have reported similar positive hearing benefits from CI use in small cohorts of patients with UD (5Y7). The main disabilities that affect adults with UD are lack of spatial hearing, impaired speech intelligibility in the presence of background noise (BN), and reduced speech understanding when speech is presented to the impaired ear (8). In a study by Priwin et al. (9), 14% of the subjects with unilateral hearing loss had severe difficulty in a group conversation, 19% found that the ability to converse in the presence of traffic noise was severely affected and even conversation in quiet was difficult for 26% of the participants. Vicci de Araujo et al. (10) showed that 73% of patients with unilateral hearing loss reported some
Address correspondence and reprint requests to Dayse Ta´vora-Vieira, Au.D., Fremantle Hospital Campus, Fremantle, Western Australia, Australia; E-mail: [email protected] The authors disclose no conflicts of interest. Supplemental digital content is available in the text.
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UNILATERAL DEAFNESS COCHLEAR IMPLANTATION level of handicap, 52% reported difficulty at the cinema, and 40% reported difficulty on the telephone. Subjects with UD are deprived of binaural hearing, which is the ability of the auditory system to process and integrate inputs from both ears. Binaural hearing is essential for spatial hearing, and it improves speech perception in noise (11Y14). The benefits of binaural hearing through bimodal amplification and bilateral CIs in adults have been well documented (15Y18). Therefore, it might be expected that patients with UD would attain additional benefit from adding a CI to their unilaterally deafened ear to be used together with their contralateral normal-hearing ear. However, to the best of our knowledge, there is no literature reporting the selection criteria and the key factors that might influence the outcomes. This study was designed to investigate whether duration of deafness or age at implantation has any impact on the outcomes. We hypothesized that, in subjects with postlingual UD, duration of deafness and age at implantation would not play a major role on the outcomes of cochlear implantation. Duration of deafness has been used on studies with bilateral severe-to-profound hearing loss as a predictive factor for the outcomes of cochlear implantation in postlingually deaf patients (19,20). However, recent investigation has shown that this is particularly true if analyzing the duration of deafness in the better hearing ear (21). It seems that, if the contralateral ear has good speech understanding, good outcomes of implantation are obtained from the ear with a long duration of deafness (21). Thus, subjects with long-term UD should not be denied a CI based solely on this criterion. Age at implantation is well accepted as another key factor that will determine the outcomes of CI in congenital bilateral deafness (22,23). In the contrary, it seems that this is not a determinant factor for CI in adults with postlingual deafness (24,25). The preliminary results of our first nine patients, with a follow-up of 3 months after cochlear implantation, have been previously published (26). This study adds to the existing literature by incorporating a larger number of subjects and investigating 1) the impact of CI use in speech intelligibility in noise, 2) the long-term impact of CI use on the subjective perception of hearing, 3) if use of the CI decreases tinnitus perception in the long-term, and 4) if duration of deafness and age at implantation affect the outcomes. MATERIALS AND METHODS This study was designed and conducted in accordance with the Declaration of Helsinki. Ethics approval was obtained from the relevant ethics and institutional review committees. Twenty-eight adult subjects (15 women and 13 men) with unilateral sensorineural severe-to-profound hearing loss were enrolled in this study. Thirteen patients had tinnitus. The better-hearing ear had a pure-tone average (PTA0.5Y4kHz) of 30 dB or less. Table 1 shows the subjects’ detailed demographic data. All subjects were implanted with a 31.5- or 28-mm electrode array (MED-EL GmbH, Innsbruck, Austria). The surgical procedure used was a hearing preservation technique, as described by Rajan et al. (27).
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Standardized preoperative evaluation of the subjects included high-resolution computed tomography and magnetic resonance imaging of the temporal bones and brain to rule out the presence of any inner ear anomalies or cochlear nerve pathologies that might constrain electrical stimulation by a CI. Audiologic workup included immittance measures, audiometry, and speech discrimination in quiet using the Arthur Boothroyd word list (28). A hearing aid was fitted to the poorer ear if any functional hearing was present and, if this was unsuccessful, a patient was considered for a CI. To participate in the study, all subjects were asked to trial a conventional contralateral routing of signal (CROS) hearing aid and the bone-anchored hearing aid (BAHA) mounted on a soft band. They used the device for 2 weeks each. This trial aimed to give the subjects the option to experience a noninvasive or less invasive rehabilitation option for UD. Speech perception testing was performed using the adaptive Bamford-Kowal-Bench speech-in-noise (BKB-SIN) test (29), which investigates the signal-to-noise ratio needed to achieve a score of 50% of the words correct. Tests were performed in a free field, with the subject seated 1 m away from loudspeakers located at angles of 0, j90, and +90 degrees. The spatial configurations used for speech testing were S0/N0, speech and noise presented from the front; S0/NHE, speech presented from the front and noise to the normal-hearing ear; and SCI/NHE, speech presented to the implanted ear and noise to the side of the normal-hearing ear. The spatial configuration SCI/NHE was chosen on the basis of being the most challenging situation as clinically described by the patients. Subjective assessment of hearing was determined using the standardized Speech, Spatial and Qualities of Hearing (SSQ) questionnaire (30). The SSQ is composed of 50 questions, and each question has a score of 0 to 10. A higher score on the SSQ indicates better subjective perception of hearing speech, spatial orientation, and quality of hearing. All subjects were asked to complete the SSQ presurgically and at 3, 6, and 12 months after cochlear implantation. The long-term benefit was verified at 24 months. The Abbreviated Profile of Hearing Aid Benefit (APHAB) is a self-assessment tool composed of 24 questions that indicate the level of difficulty a person with hearing loss faces in various everyday listening situations. It aims to calculate the benefit of amplification as perceived by the subject by comparing the subjects’ reported difficulty in unaided and aided conditions. High scores mean that the patients experience performance difficulties more often. The questionnaire has four subscales, ease of communication (EC), reverberation (RV), BN, and aversiveness, and one global scale (31). Although the APHAB is a validated questionnaire for hearing aid users, it was thought that at least three of the subscales such as EC, RV, and BN, together with the global scale, would provide more information on how the subjects rated their hearing with a CI. The APHAB was completed presurgically and at 12 months after cochlear implantation to determine the subjective benefit of CI use. Tinnitus disturbance was assessed using the Tinnitus Reaction Questionnaire (TRQ [32]). The TRQ is composed of 26 questions designed to establish the effects of tinnitus during the past week on lifestyle and general well-being using a scale from 0 (not at all) to 4 (almost all of the time). The final totaled score can range from 0 through 104. All subjects were asked to complete the TRQ presurgically and at 3, 6, and 12 months after CI activation. Long-term effect was also measured at 24 months.
Auditory Training Intensive auditory training was provided for all participants. The rehabilitation methods were discussed at length with each Otology & Neurotology, Vol. 36, No. 3, 2015
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TABLE 1. Subject
Duration of Age at Sex deafness (yr) implantation (yr) Ear
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28
M M F M M M M M F F F M F M F F F M M F F M F F M F F F
3 2 40 0.6 33 35 2 20 6 0.6 20 1 0.6 39 27 0.3 12 0.3 0.4 1.5 1 5 4 2.5 7 1 0.9 1.5
45 56 55 70 55 68 38 40 46 38 55 60 53 51 48 39 41 62 72 73 57 71 39 74 53 57 42 47
R L L R L R R R R R L L R R R R L R L L L R R L R L L R
Subject demographic data Pure-tone average (0.5Y4 kHz)- Pure-tone average (0.5Y4 kHz)nonimplanted ear in dBa implanted ear in dBa
Etiology ISSNHL Posttraumatic Unknown ISSNHL Unknown Iatrogenic Posttraumatic Posttraumatic ISSNHL ISSNHL Me´nie`re’s disease Unknown ISSNHL Mumps Ototoxicity Fistula Unknown ISSNHL ISSNHL Unknown ISSNHL Unknown Unknown Unknown Unknown ISSNHL ISSNHL ISSNHL
10 18 13 25 19 27 3 34 32 24 18 18 13 4 13 27 5 7 24 21 25 30 19 21 24 32 10 21
74 90 79 84 97 9110 9110 9110 95 93 9110 97 75 9110 75 9110 72 72 82 9110 76 74 9110 9110 95 80 92 87
F indicates female; ISSNHL, idiopathic sudden sensorineural hearing loss; L, Left; M, male; R, Right. a Before cochlear implantation.
individual before his or her enrollment in the study to ensure the participant’s compliance and strong commitment to the training. Participants agreed to commit 30 to 60 minutes per day to auditory training. Auditory training started at Week 2 or 3 after CI activation. Patients were seen, on average, weekly for the first 6 weeks and then monthly up to 6 months after CI activation. All subjects were provided with an audio cable that connected the speech processor to an audio source. A map for direct audio input connection was created for each subject at Week 2 or 3, depending on the individual’s tolerance to electrical stimulation. To establish the most comfortable levels of the direct audio input map, a series of progressive maps were created. The speech processor was then connected to an audio player, and the subject was asked to listen to a speech signal and select the map that best matched the most comfortable level while using the audio cable. The subjects were then provided with prerecorded material composed of meaningful English wordsVfor example, numbers, colors, animals, fruits. When the subjects were able to discriminate the words, a list of prerecorded meaningful sentences was provided. The next step was to listen to audiobooks. The audiobooks varied in vocabulary difficulty, sentence length, and reading speed rate. Those with greater difficulties were provided with books that encompassed a simple vocabulary, known themes, and a low reading speed (as low as 40 words per minute). As their speech discrimination improved, subjects progressed onto audiobooks with a more complex vocabulary and a higher reading speed rate. Visual cues were permitted at the beginning of the program and removed as the subjects progressed. To ensure that all subjects received similar auditory training, a computer was available at the implant center for those who did not have access to a computer or CD player at home.
Statistical Analyses Three-way repeated-measures analysis of variance was used to determine the effect of time, age at implantation, and duration of deafness, as well as their interaction on the three spatial setups of the adaptive BKB-SIN test, the three SSQ subscales, and the TRQ scores. For the APHAB subscales and the AHPAB global scale, a paired-sample t test was used to examine a significant difference between preoperative testing and 12-month postoperative testing. To test a possible influence of age and duration of deafness as well as their interaction at the single tested intervals, a multivariate general linear model was performed for all outcome variables. All p values are results of two-sided tests. A value of p G 0.05 was considered to indicate statistical significance.
RESULTS Speech Perception in Noise The speech perception results in noise of the adaptive BKB-SIN test in the three spatial setups are shown in Figure 1. Mean scores for the S0/N0 spatial test setup ranged from 4.47 (TSD, 1.796) preoperatively to 1.90 (TSD, 1.917) 12 months postoperatively. Mean scores for the S0/NHE spatial test setup ranged from 0.14 (TSD, 3.681) preoperatively to j1.57 (TSD, 3.217) 12 months postoperatively. Mean scores for the SCI/NHE spatial test setup ranged from 5.11 (TSD, 3.722) preoperatively to j0.80 (TSD, 3.262) 12 months postoperatively. Time (preoperatively and 3, 6, and 12 months postoperatively) had a significant main effect on the S0/N0 spatial test outcome (F3,42 = 21.878; p G 0.001), on the
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FIG. 1. The Bamford-Kowal-Bench speech-in-noise test results across time. Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers.
S0/NHE spatial test outcome (F3,42 = 7.226; p = 0.003), and on the SCI/NHE spatial test outcome (F3,42 = 74.326; p G 0.001). There was no significant interaction between age at implantation and duration of deafness across time or any of their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (see Supplemental Digital Contents 1, 2, and 3, http://links.lww.com/MAO/A274, which show the p values for the three spatial configuration). Subjective Testing The results of the three subscales of the SSQ are shown in Figure 2. Mean scores for the subscale Speech ranged from 4.69 (TSD, 1.827) preoperatively to 7.65 (TSD, 1.105) 24 months postoperatively. Mean scores for the subscale Spatial ranged from 2.61 (TSD, 1.604) preoperatively to 7.37 (TSD, 1.204) 24 months postoperatively. Mean scores for the subscale Quality of Hearing ranged from 6.16 (TSD, 1.797) preoperatively to 8.15 (TSD, 0.947) 24 months postoperatively. Time had a significant main effect on the Speech subscale (F1.4,12.7 = 6.051; p = 0.021), on the Spatial subscale (F1.6,14.7 = 24.160; p G 0.001), and on the Quality of Hearing subscale (F1.5,13.3 = 6.326; p = 0.017). There was no significant interaction between age at implantation and duration of deafness across time or any of
their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (see Supplemental Digital Content 4, 5, and 6, http://links.lww.com/MAO/A274, which show the p values for the three SSQ subscales). The results of the 3 APHAB subscales are shown in Figure 3. Mean scores on the EC subscale were 33.6 (TSD, 14.912) at preoperative testing and 14.4 (TSD, 12.602) at 12 months postoperatively. Mean scores on the subscale RV were 46.6 (TSD, 17.570) at preoperative testing and 23.2 (TSD, 12.984) 12 months postoperatively. Mean scores on the BN subscale were 63.6 (TSD, 14.212) at preoperative testing and 32.1 (TSD, 12.576) at 12 months postoperatively. Mean scores on the global scale were 47.2 (TSD, 13.797) at preoperative testing and 22.9 (TSD, 11.802) 12 months postoperatively. The subjective perception of EC improved significantly between preoperative testing and 12 months postoperatively (t = 4.97; p G 0.001). The subjective perception of RV improved significantly between preoperative testing and 12 months postoperatively (t = 5.38; p G 0.001). The subjective perception of BN improved significantly between preoperative testing and 12 months postoperatively (t = 6.45; p G 0.001). There was no significant interaction between age at implantation and duration of deafness preoperatively or 12 months postoperatively or any of their
FIG. 2. Speech, Spatial, and Qualities of hearing subscale results across time. Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers. Otology & Neurotology, Vol. 36, No. 3, 2015
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FIG. 3. The Abbreviated Profile of Hearing Aid Benefit subscale and global scale results between preoperative testing and 12-month postoperative testing (percentage). Median values are displayed as a horizontal line, mean values as black squares. Asterisks denote outliers.
possible interactions preoperatively or 12 months postoperatively (p = 0.090Yp = 0.968; see Supplemental Digital Content 7, 8, and 9, http://links.lww.com/MAO/A274, which show the p values for the three APHAB subscales). The global scale improved significantly between preoperative testing and 12 months postoperatively (t = 6.15; p G 0.001). There was no significant interaction between age at implantation and duration of deafness preoperatively or 12 months postoperatively or any of their possible interactions preoperatively or 12 months postoperatively (p = 0.122Yp = 0.543; see Supplemental Digital Content 10, http://links.lww.com/MAO/A274, which shows the p values for the APHAB global scale). Tinnitus Disturbance The results of the TRQ are shown in Figure 4. Mean scores for the TRQ were 48.8 (TSD, 27.150) at preoperative testing and 1.75 (TSD, 4.200) 24 months postoperatively. Time had a significant main effect on the TRQ (F1.3,7.8 = 10.098; p = 0.011). There was no significant interaction between age at implantation and duration of deafness across time or any of their possible interactions across time. There was no significant interaction between age at implantation and duration of deafness at the individual time intervals tested or any of their possible interactions at the individual time intervals tested (p = 0.170Yp = 1.000; see Supplemental Digital Content 11,
FIG. 4.
http://links.lww.com/MAO/A274, which shows the p values for the TRQ scores). DISCUSSION Recent literature has demonstrated cochlear implantation to be a suitable hearing rehabilitation option for adults with unilateral profound deafness. A CI is the only option that provides ear-specific information and thus potentially the benefits of binaural hearing. There are known benefits to listening with two ears, as reviewed in the International Consensus on Bilateral Cochlear Implants, which suggested that speech recognition in noise is better under binaural listening conditions than under binaural deprivation (33). Litovsky et al. (34) have shown that, by using bilateral implants, a 12% to 33% improvement in speech perception can be achieved by deaf adults. Bilaterally implanted deaf children perform better than children with a unilateral CI in speech in noise testing (35). However, the benefits of CIs in UD and the improvement on speech performance in noise have been addressed by very few groups during the past few years (3Y7). To date, the selection criteria for cochlear implantation in UD are not clearly established and factors that might determine the outcomes are unknown. This study addressed this issue by analyzing the potential influence that age at implantation and duration of deafness might have on the CI outcomes.
Tinnitus Reaction Questionnaire results across time. Median values are displayed as a horizontal line, mean values as black squares.
Otology & Neurotology, Vol. 36, No. 3, 2015
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UNILATERAL DEAFNESS COCHLEAR IMPLANTATION This study investigated the hearing benefits of CI in terms of speech perception, self-assessment of hearing performance, and tinnitus disturbance in a cohort larger than 25 subjects with long-term follow-up. It is the first to investigate whether duration of deafness and age at implantation have an effect on the outcomes. Our results showed a significant improvement in speech perception in noise scores when speech and noise are presented from the front (S0/N0) and when speech is presented from the front (S0/NHE) or from the CI side (SCI/NHE) with the noise presented to the normal-hearing ear. These results indicate that patients with UD may be able to make use of some of the benefits associated with binaural hearing. Both SSQ and APHAB showed a significant subjective improvement of hearing with CI use. The analysis of the SSQ scores confirmed that the improvement over time was significant for all 3 subscales: speech, spatial hearing and qualities of hearing. Similarly, Arndt et al. (4) reported a significant improvement in the speech and spatial hearing subscales while Vermeire and Van de Heyning (2) found an improvement in all three subscales, indicating that the subjective perception of hearing improves with CI use in UD subjects. The SSQ questionnaire was repeated at 24 months post-CI, and the scores showed that the subjective benefit remained stable in the long-term. The results of the APHAB were in line with the SSQ scores, with an improvement in the subscales ease of hearing, RV, and BN. The scores of the aversiveness subscale did not change significantly before and after surgery. This demonstrates that CI in UD enhances patients’ selfperception of hearing performance and does not create any tolerance issues. The disturbance caused by tinnitus also decreased for the subjects. A further follow-up at 24 months showed that the improvement was stable in the long-term. A significant positive effect on tinnitus has been reported previously (1,3,36). In accordance with the data herein, Punte et al. (37) reported a significant decrease in tinnitus distress in 26 subjects who received a CI for UD associated with tinnitus. Thus, it seems that CI can be used as an effective means of reducing tinnitus disturbance. Our results showed that age at implantation or duration of deafness did not have a significant effect on the speech perception in noise scores, subjective hearing performance as measured by the SSQ and APHAB, and on the improvement of tinnitus, confirming our initial hypothesis that these factors would not play a key role in the rehabilitation of postlingual UD using CI. There was a concern that subjects with normal contralateral hearing would have difficulties integrating the acoustic and electric signals. In contrast to standard CI recipients who had to rely on some kind of amplification, subjects with UD might be expected to give up using their CI if their progress was too slow or if the obvious benefits did not overcome the challenges associated with CI use. Studies have demonstrated the benefits of active auditory training for patients using auditory rehabilitation (38,39). In an earlier UD case study by Nawaz et al. (40), one subject received training to stimulate both ears simulta-
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neously and promote binaural integration with success. In our study, intensive auditory training was provided that aimed to facilitate acclimatization to the CI. Further investigation is necessary to establish the exact contribution of auditory training. Cumulatively, these results, along with device acceptance, suggest that subjects with UD are probably able to combine the acoustic and electrical signals. CONCLUSION The results of the present study indicate that, in subjects with UD, speech perception in noise is improved with CI use. CI use improves the subjective perception of hearing in UD subjects and decreases the disturbance of tinnitus, which may in turn contribute to an overall positive subjective impression of benefits in this group of subjects. It seems that age at implantation and duration of deafness do not affect the outcome. Acknowledgments: The authors thank E. A. for statistical analyses and I. G. A. and U. D. for editing a version of this article.
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