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tions of deafness. Although the majority (12 of 23 or 52%) had SSNHL, other causes of hearing loss were also represented. The numbers, however, are not large enough to analyze outcomes by etiology. In addition, lon- ger durations of deafness were observed in many of these cases. We know from previous work that duration of deafness negatively impacts CI performance and may have played a role in our patients being implanted after longer periods of nonusable hearing. 23 Our mean dura- tion of deafness (4.0 years) is skewed by three of six of the children in whom congenital hearing loss and long delays to implantation occurred. Future studies with higher numbers of patients in this category will be needed to determine if significant differences in perform- ance occur. CONCLUSION Rehabilitation of SSD with CI significantly improves speech understanding in the deafened ear and reduces or eliminates tinnitus in most subjects. Speech understanding in noise remains unchanged between the 3-months and 6-months postactivation test intervals. It is possible that performance on speech in noise will con- tinue to improve that and benefits will be realized with longer-term implant experience. BIBLIOGRAPHY 1. Hanson H. Unilateral deafness a, social, psychological, and existential aspects [Thesis]. Stockholm, Sweden: University of Stolkholm; 1993. 2. Lin FR, Niparko JK, Ferrucci L. Hearing loss prevalence in the United States. Arch Intern Med 2011;171:1851–1852. 3. Wie OB, Pripp AH, Tvete O. Unilateral deafness in adults: effects on com- munication and social interaction. Ann Otol Rhinol Laryngol 2010;119: 772–781. 4. Fetterman BL, Saunders JE, Luxford WM. Prognosis and treatment of sudden sensorineural hearing loss. Am J Otol 1996;17:529–536. 5. Akeroyd MA. The psychoacoustics of binaural hearing. Int J Audiol 2006; 45(suppl 1):S25–S33. 6. Middlebrooks JC, Green DM. Sound localization by human listeners. Annu Rev Psychol 1991;42:135–159. 7. Bishop CE, Eby TL. The current status of audiologic rehabilitation for pro- found unilateral sensorineural hearing loss. Laryngoscope 2010;120: 552–556. 8. Desmet JB, Wouters K, De Bodt M, et al. Comparison of 2 implantable bone conduction devices in patients with single-sided deafness using a daily alternating method. Otol Neurotol 2012;33:1018–1026. 9. Saroul N, Akkari M, Pavier Y, et al. Long-term benefit and sound localiza- tion in patients with single-sided deafness rehabilitated with an osseoin- tegrated bone-conduction device. Otol Neurotol 2013;34:111–114. 10. Vermeire K, Van de Heyning P. Binaural hearing after cochlear implanta- tion in subjects with unilateral sensorineural deafness and tinnitus. Audiol Neurootol 2009;14:163–71. 11. Firszt JB, Holden LK, Reeder RM, et al. Auditory abilities after cochlear implantation in adults with unilateral deafness: a pilot study. Otol Neu- rotol 2012;33:1339–1346. 12. Tavora-Vieira D, Marino R, Krishnaswamy J, et al. Cochlear implantation for unilateral deafness with and without tinnitus: a case series. Laryn- goscope 2013;123:1251–1255. 13. Stelzig Y, Jacob R, Mueller J. Preliminary speech recognition results after cochlear implantation in patients with unilateral hearing loss: a case series. J Med Case Rep 2011;5:343. 14. Blasco MA, Redleaf MI. Cochlear implantation in unilateral sudden deaf- ness improves tinnitus and speech comprehension: meta-analysis and systematic review. Otol Neurotol 2014;35:1426–1432. 15. Arndt S, Aschendorff A, Laszig R, et al. Comparison of pseudobinaural hearing to real binaural hearing rehabilitation after cochlear implanta- tion in patients with unilateral deafness and tinnitus. Otol Neurotol 2011;32:39–47. 16. Zeitler DM, Dorman MF, Natale SJ, et al. Sound source localization and speech understanding in complex listening environments by single-sided deaf listeners after cochlear implantation. Otol Neurotol 2015;36:1467– 1471. 17. Gatehouse S, Noble W. The Speech, Spatial and Qualities of Hearing Scale (SSQ). Int J Audiol 2004;43:85–99.

observed in adults and children with bilateral hearing loss. Specifically, the current study found that CNC word recognition was, on average, 44% at 6-months post- activation, whereas studies using adults with bilateral hearing loss, also with 6 months of use, have an average CNC word score of 61%. 23 The primary explanation for this finding is that patients with normal hearing in one ear continue to rely heavily on their good ear because of the natural sound quality, which may reduce the rate of improvement and maximum rehabilitation potential of the deaf ear. In contrast to speech recognition in quiet, the cur- rent study found that speech recognition in noise was not significantly improved after CI, although the scores at 6-months postactivation were higher than those obtained before surgery. As noted earlier, several previ- ous investigators have reported similar findings. How- ever, one recent study by Mertens et al. suggests that speech-in-noise improvement may not emerge until after several years of implant use. 24 In that study, 12 adults with SSD and CI were followed through 36 months of implant use. Speech-in-noise performance was measured with CI on and CI off using various testing parameters, including presentation of both speech and noise from the front, as well as spatially separated signals (S 0 N 0 , S 0 N CI , S CI N 0 ). Results demonstrated improved speech in noise for S 0 N CI after 12 months of implant use, whereas improved performance for S 0 N 0 was not observed until 36 months of implant use. Tinnitus suppression continues to be an indirect benefit of implantation among patients with SSD. As seen in the current study, the majority of patients who had tinnitus prior to surgery had a reduction in self- reported tinnitus severity following implantation with the device on, and in many cases also with the device off. The exact underlying reason of tinnitus suppression is not known, although there is speculation that the implant increases afferent stimulation, which offsets one possible underlying cause. 18 There are several limitations associated with the current study. First, the relatively small sample size makes statistical comparisons less robust and limits gen- eralizability of the data. Larger sample sizes are needed to understand the variability in performance within this population. Another limitation is that data was collected retrospectively from two separate centers, each with unique test protocols. For example, center 2 measured speech recognition in the implanted ear with the contra- lateral ear plugged and muffed, whereas center 1 used masking on the contralateral side. It is unknown if these two methods are equivalent. Another limitation of this study is the condition of the participants’ sound process- ors. Each participant was tested using the sound proces- sor and program that they use in everyday life. There was no control regarding the volume setting, the pres- ence of noise suppression circuits, or input mixing ratios. It is possible that some participants have much higher volume settings than others. Demographic factors also limit the current study. For example, the group studied here was comprised of children and adults with various etiologies and dura-

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