this frequency region is essential for good speech understanding in complex listening environments , particularly in noise.4 , 5 individuals with substantial , bilateral highfrequency hearing loss experience hearing difficulties in most aspects of life : at home , on the phone , at work , and in social situations
. they can be highly frustrated because existing hearing aid technology can not overcome the problems of reduced word understanding in quiet and noise.6 , 7 , 8 due to their communication problems , they may become isolated , withdrawing from family , colleagues , and friends . with severe hearing loss , areas of minimal or nonfunctioning hair cells or auditory
neurons are often present , resulting in cochlear dead regions where vibrations of the basilar membrane are not detected via inner hair cells or neurons in that region .
frequencies falling in a dead region are detected via apical or basal spread of vibrations to other cochlear places .
therefore , hearing loss at a given frequency may be greater than indicated by the audiometric threshold.9 typically , acoustic amplification of dead regions does not improve speech understanding and may worsen it.10 , 11 individuals with this hearing loss profile may be candidates for electric plus acoustic stimulation in the same ear .
treatment options for individuals with bilateral , severe skislope hearing loss have been limited to stateofthe art amplification , including frequency lowering,12 in an effort to improve speech intelligibility .
these attempts often end with the rejection of hearing aids due to the lack of benefit , leaving the individual with no other alternatives .
studies have shown that an implant with a shorter electrode array provides beneficial electric stimulation for high frequencies while preserving acoustic lowfrequency hearing , resulting in improved speech understanding.13 , 14 recently , lenarz et al . described results from a european multicenter study using the cochlear ltd .
, sydney , australia , nucleus hybrid l24 implant.15 we report results of the clinical trial leading to u.s . food and drug administration approval of the firstofitskind combined electric and acoustic ( hybrid ) implant system to address the substantial hearing difficulties of individuals not benefitting from amplification and not eligible for a standard cochlear implant ( ci ) .
this was a prospective , singlearm , multicenter trial to determine the safety and effectiveness of the hybrid system .
subjects were implanted at 10 clinical sites in the united states and served as their own controls in all test conditions .
the protocol was approved by the us food and drug administration and relevant institutional review boards , and all participants gave written informed consent .
the ear selected for implantation had severe (  75 db hl averaged over 2000 , 3000 , 4000 hz ) highfrequency sensorineural hearing loss and relatively good lowfrequency hearing (  60 db hl at 125 , 250 , and 500 hz ) .
in addition , an aided consonantnucleusconsonant ( cnc ) monosyllabic word score of 10% through 60% using an appropriately fit hearing aid was required .
aided word recognition in the contralateral ear was required to be similar or better than the ear to be treated , but not better than 80% .
those with durations of severe or profound hearing loss greater than 30 years and/or onset of hearing loss less than 2 years were excluded .
the protocol included acoustic thresholds measured for each ear preoperatively and postoperatively , at device activation , and 3 , 6 , and 12 months postactivation .
consonantnucleusconsonant words were presented at 60 dba ; azbio sentences in noise were presented at 60 dba in 10talker babble noise at + 5 db signaltonoise ratio . to evaluate effectiveness of the hybrid system as used routinely ,
speech perception outcomes were analyzed in the everyday listening condition , which is listening through the hybrid system in combination with acoustic hearing in the opposite , unimplanted ear . to gain insight into
how hearing impacts quality of life , the validated speech , spatial , and qualities of hearing questionnaire ( ssq)16 was administered as a selfassessment of hearing within three domains : hearing speech in various environments , spatial hearing , and sound qualities .
a device use questionnaire was administered that addressed overall satisfaction with the hybrid system relative to hearing aids .
surgery for the hybrid l24 implant ( cochlear ) is a modification of that for standard cis , similar to the description by gantz et al.13 ; details are provided in the nucleus hybrid l24 implant surgeon 's guide ( cochlear).17 after the postauricular incision , the surgeon creates a well bed on the skull posterior to the mastoid and opens the facial recess ( posterior tympanotomy ) widely to provide good visibility of the round window niche in the middle ear .
although the hybrid implant electrode may be inserted through the round window or cochleostomy , in this trial all electrodes were inserted through a small cochleostomy created just inferior to the round window . after performing the cochleostomy
, the surgeon opens the endosteum of the cochlea with a pick just prior to inserting the electrode array .
the array is slowly inserted 16 mm into the scala tympani instead of the 19 to 24 mm that are more typical for standard cis .
the 16mm straight electrode is very thin and has 22 halfband modiolarfacing electrode contacts to stimulate the basal region of the cochlea , with the intent to maintain apical cochlear structures responsible for lowfrequency hearing .
coprimary efficacy hypotheses were that outcomes on cnc words ( 100 recorded words administered)18 and azbio sentences in noise ( 40 recorded sentences administered)19 presented through the hybrid implant system ( cochlear ) would be significantly better at 6 months postimplantation than preoperative performance using a hearing aid .
the sample size of 50 subjects exceeded the minimum requirement for 90% statistical power , ensuring adequate power .
mean differences for subjects on the cnc word and azbio sentence recognition scores preoperatively and at the 6month endpoint were analyzed using paired t tests .
if there was evidence that assumptions did not hold , a wilcoxon signed rank test was used .
secondary efficacy objectives compared individual preoperative performance with a hearing aid to performance at the 6month endpoint on cnc words and phonemes and azbio sentences .
although no formal hypothesis test was conducted for these endpoints , success would be achieved if over 75% of subjects showed equal or better performance from preoperative to postoperative scores using the binomial model.20 
  the primary safety objective was to describe the safety of implantation with the hybrid system .
the primary safety endpoint was defined as any surgical and/or devicerelated event , reported as the number and proportion of individuals experiencing an adverse event .
coprimary efficacy hypotheses were that outcomes on cnc words ( 100 recorded words administered)18 and azbio sentences in noise ( 40 recorded sentences administered)19 presented through the hybrid implant system ( cochlear ) would be significantly better at 6 months postimplantation than preoperative performance using a hearing aid .
the sample size of 50 subjects exceeded the minimum requirement for 90% statistical power , ensuring adequate power .
mean differences for subjects on the cnc word and azbio sentence recognition scores preoperatively and at the 6month endpoint were analyzed using paired t tests .
if there was evidence that assumptions did not hold , a wilcoxon signed rank test was used .
secondary efficacy objectives compared individual preoperative performance with a hearing aid to performance at the 6month endpoint on cnc words and phonemes and azbio sentences .
although no formal hypothesis test was conducted for these endpoints , success would be achieved if over 75% of subjects showed equal or better performance from preoperative to postoperative scores using the binomial model.20 
  the primary safety objective was to describe the safety of implantation with the hybrid system .
the primary safety endpoint was defined as any surgical and/or devicerelated event , reported as the number and proportion of individuals experiencing an adverse event .
mean age was 64.1 years ( standard deviation [ sd ]  =  14.7 years ) , ranging from 23 to 86.2 years at implantation .
there was a 50/50 split for gender , and 52% of right ears were implanted .
mean duration of overall hearing loss was 28.1 years , and mean duration of severetoprofound highfrequency loss was 13.1 years .
hearing loss etiologies were : unknown ( 50% ) , noise exposure ( 22% ) , and familial ( 20% ) .
individual cases ( 8% ) were related to ototoxic drugs , autoimmune ear disease , high fever / infection , and noise exposure / viral .
hl  =  hearing loss ; lf  =  low frequency ; pta  =  pure tone average ; sd  =  standard deviation . table 2 provides a summary of primary outcomes ( cnc words and azbio sentences in noise for the implanted ear ) . when testing the implanted ear , the contralateral ear was plugged to mitigate its contribution to the speech scores . for cncs
, subjects experienced a significant ( p  <  0.001 ) improvement of 35.8 ( sd  =  27.7 ) percentage points with the hybrid device over a hearing aid preoperatively .
similarly , for azbio sentences , they experienced a significant ( p  <  0.001 ) improvement of 32.0 ( sd  =  29.4 ) percentage points .
one subject missed 6month assessments , and data were imputed based on the 3month evaluation .
<  0.001 one subject missed 6month assessments and data were imputed based on the 3month evaluation .
table 3 presents secondary objective outcomes based on binomial comparisons of preoperative to postoperative changes for cnc words and azbio sentences for the implanted ear at the 6month endpoint .
the secondary endpoint objectives were met : over 75% of the subjects demonstrated equal or improved performance on cnc words , phonemes , and azbio sentences with the hybrid implant relative to performance with a hearing aid . specifically , 96% and 92% of subjects performed equal or better on cnc words and phonemes , respectively , and 90% on azbio sentences . furthermore ,
82% and 86% showed improved performance on cnc words and phonemes , respectively , and 74% improved on sentences .
the consistency of the primary endpoints for the treated ear was examined across subject subgroups defined by baseline characteristics : gender , age , duration of hearing loss , duration of severetoprofound highfrequency hearing loss , etiology , and baseline speech perception scores .
results indicated that baseline characteristics gender , age , and duration of hearing loss were the main factors in terms of speech perception outcomes .
this was not the case for duration of severetoprofound highfrequency hearing loss , etiology , and baseline speech scores .
mean benefit scores ( i.e. , improvement ) for females were significantly greater than males for cnc words ( females : 48.8% ; males : 25.7% ) and azbio tests ( females : 42.6% ; males : 23.5% ) ( p  =  0.002 and 0.02 , respectively .
) subjects under the median implantation age of 68 years showed significantly greater benefit for cncs ( < 68 years : 46.6% ; >  68 years : 27.8% ) ( p  =  0.01 ) but not azbio sentences ( <  68 years : 41.0% ;  >  68 years : 25.0% )
the mean benefit for subjects below the median hearing loss duration of 23.5 years was significantly better ( p  =  0.01 ) than for hearing loss durations above 23.5 years for cncs ( <  23.5 years : 46.2% ; >  23.5 years : 27.5% ) but not azbio sentences ( <  23.5 years : 40.7% ; >  23.5 years : 24.7% ) ( p  =  0.05 ) , although the trend favored shorter durations .
mean differences for cnc words and azbio sentences in noise at 6months postactivation , using the implant and contralateral hearing aid , were preoperatively compared to bilateral amplification .
for cncs , subjects ( n  =  49 ) showed significant ( p  <  0.001 ) improvement of 34.7 percentage points ( sd  =  17.4 ) compared to bilateral amplification .
for azbio sentences , subjects ( n  =  49 ) showed significant ( p  <  0.001 ) improvement of 33.0 percentage points ( sd  =  23.5 ) compared to bilateral amplification .
no subject showed a significant decrement preoperatively to postoperatively on either measure . at the 6month endpoint , all subjects performed equal or better than preoperatively with bilateral amplification with hearing aids .
fortyeight subjects completed the ssq preoperatively using hearing aids and after 6 months using the hybrid system in the everyday listening condition . for the speech hearing scale , subjects improved significantly ( p  <  0.001 ) , showing a mean change score of 2.2 ( sd  =  1.8 ) . on the spatial hearing scale , there was a significant ( p  < 
0.003 ) mean change score of .9 ( sd  =  2.0 ) ; on the sound quality scale , subjects experienced significantly ( p  <  0.001 ) improved mean change of 1.3 ( sd  =  2.0 ) .
of the 48 subjects who completed the device use survey , four ( 8% ) were 
the type and frequency of events were consistent with those reported in cochlear implantation ( e.g. , electrode open or short circuits , postoperative dizziness , changes in tinnitus ) or other mastoid operations ; no unanticipated adverse events were reported .
fifty events were medical / surgical in nature and included instances of increased tinnitus , vertigo , and other symptoms associated with a mastoidectomy with facial recess approach used in cochlear implantation . it should be noted that the nine adverse events reporting of dizziness , imbalance , and vertigo were likely reported by a few patients and not nine separate patients ; one could have symptoms of dizziness , imbalance , and vertigo .
unlike prior ci trials , this was the first to quantify changes in residual hearing ; any changes in preoperative to postoperative hearing sensitivity were measured throughout the study period .
changes resulting in profound ( > 90 db hl ) hearing loss were reported as anticipated adverse events . at 6months postactivation , 66% of subjects ( 33 of 50 ) retained functional acoustic sensitivity determined by a 5frequency pure tone average ( 125 , 250 , 500 , 750 , 1000 hz ) of a severe degree or better (  90 db hl ) .
the degree of hearing loss and the number of subjects in each hearing loss category and their postintervention outcomes are depicted in figure 2a and b. in addition , the amount of residual hearing and the number of subjects in each category and their postintervention outcomes are depicted in figure 3a and 3b .
subjects with aidable , residual hearing performed better that those without aidable , residual hearing . however , even if subjects had no residual , aidable hearing , they performed better in the ci electriconly condition than preoperatively with hearing aids . regarding 17 subjects who did not maintain functional acoustic hearing , five chose to have the hybrid implant explanted and replaced with a standard ci .
improved speech perception of varying degrees was observed compared to that obtained preoperatively with a hearing aid and at the most recent hybrid evaluation prior to revision surgery .
( a ) cnc word scores for subjects with  <  10 , 1020 , 2030 , and  >  30 db of hearing loss at 6 months postcochelar implant activation .
( b ) azbio + 5 db signaltonoise ratio scores for subjects with  <  10 , 1020 , 2030 , and  >  30 db of hearing loss at 6 months postcochlear implant activation . the number of subjects in each category of hearing loss is shown .
[ color figure can be viewed in the online issue , which is available at www.laryngoscope.com . ]
( a ) the cnc word scores for subjects in each category of lowfrequency hearing loss .
( b ) the azbio + 5 db signal to noise ratio scores for subjects in each category of lowfrequency hearing loss .
[ color figure can be viewed in the online issue , which is available at www.laryngoscope.com .
apart from cases of profound hearing loss , all but two events ( one sound quality issue and one decreased performance ) were resolved as of database closure .
association of baseline characteristics with adverse events , including profound hearing loss , was examined by univariate cox proportional hazards regression models .
baseline characteristics evaluated included age at implantation , hearing loss duration , severetoprofound hearing loss duration , etiology , and preoperative speech perception .
none were found to be significantly associated with either outcome of an adverse event or profound hearing loss .
mean age was 64.1 years ( standard deviation [ sd ]  =  14.7 years ) , ranging from 23 to 86.2 years at implantation .
there was a 50/50 split for gender , and 52% of right ears were implanted .
mean duration of overall hearing loss was 28.1 years , and mean duration of severetoprofound highfrequency loss was 13.1 years .
hearing loss etiologies were : unknown ( 50% ) , noise exposure ( 22% ) , and familial ( 20% ) .
individual cases ( 8% ) were related to ototoxic drugs , autoimmune ear disease , high fever / infection , and noise exposure / viral .
hl  =  hearing loss ; lf  =  low frequency ; pta  =  pure tone average ; sd  =  standard deviation .
table 2 provides a summary of primary outcomes ( cnc words and azbio sentences in noise for the implanted ear ) . when testing the implanted ear , the contralateral ear was plugged to mitigate its contribution to the speech scores . for cncs , subjects experienced a significant ( p  <  0.001 ) improvement of 35.8 ( sd  =  27.7 ) percentage points with the hybrid device over a hearing aid preoperatively .
similarly , for azbio sentences , they experienced a significant ( p  <  0.001 ) improvement of 32.0 ( sd  =  29.4 ) percentage points .
one subject missed 6month assessments , and data were imputed based on the 3month evaluation .
<  0.001 one subject missed 6month assessments and data were imputed based on the 3month evaluation .
table 3 presents secondary objective outcomes based on binomial comparisons of preoperative to postoperative changes for cnc words and azbio sentences for the implanted ear at the 6month endpoint .
the secondary endpoint objectives were met : over 75% of the subjects demonstrated equal or improved performance on cnc words , phonemes , and azbio sentences with the hybrid implant relative to performance with a hearing aid . specifically , 96% and 92% of subjects performed equal or better on cnc words and phonemes , respectively , and 90% on azbio sentences . furthermore ,
82% and 86% showed improved performance on cnc words and phonemes , respectively , and 74% improved on sentences .
the consistency of the primary endpoints for the treated ear was examined across subject subgroups defined by baseline characteristics : gender , age , duration of hearing loss , duration of severetoprofound highfrequency hearing loss , etiology , and baseline speech perception scores .
results indicated that baseline characteristics gender , age , and duration of hearing loss were the main factors in terms of speech perception outcomes .
this was not the case for duration of severetoprofound highfrequency hearing loss , etiology , and baseline speech scores .
mean benefit scores ( i.e. , improvement ) for females were significantly greater than males for cnc words ( females : 48.8% ; males : 25.7% ) and azbio tests ( females : 42.6% ; males : 23.5% ) ( p  =  0.002 and 0.02 , respectively .
) subjects under the median implantation age of 68 years showed significantly greater benefit for cncs ( < 68 years : 46.6% ; >  68 years : 27.8% ) ( p  =  0.01 ) but not azbio sentences ( <  68 years : 41.0% ;  >  68 years : 25.0% ) ( p  =  0.05 ) , although the trend favored younger subjects .
the mean benefit for subjects below the median hearing loss duration of 23.5 years was significantly better ( p  =  0.01 ) than for hearing loss durations above 23.5 years for cncs ( <  23.5 years : 46.2% ; >  23.5 years : 27.5% ) but not azbio sentences ( <  23.5 years : 40.7% ; >  23.5 years : 24.7% ) ( p  =  0.05 ) , although the trend favored shorter durations .
mean differences for cnc words and azbio sentences in noise at 6months postactivation , using the implant and contralateral hearing aid , were preoperatively compared to bilateral amplification . for cncs , subjects ( n  =  49 ) showed significant ( p  <  0.001 ) improvement of 34.7 percentage points ( sd  =  17.4 ) compared to bilateral amplification . for azbio sentences , subjects ( n  =  49 ) showed significant ( p  <  0.001 ) improvement of 33.0 percentage points ( sd  =  23.5 ) compared to bilateral amplification .
no subject showed a significant decrement preoperatively to postoperatively on either measure . at the 6month endpoint , all subjects performed equal or better than preoperatively with bilateral amplification with hearing aids .
fortyeight subjects completed the ssq preoperatively using hearing aids and after 6 months using the hybrid system in the everyday listening condition .
for the speech hearing scale , subjects improved significantly ( p  <  0.001 ) , showing a mean change score of 2.2 ( sd  =  1.8 ) . on the spatial hearing scale , there was a significant ( p  <  0.003 ) mean change score of .9 ( sd  =  2.0 ) ; on the sound quality scale , subjects experienced significantly ( p  <  0.001 ) improved mean change of 1.3 ( sd  =  2.0 ) . of the 48 subjects who completed the device use survey , four ( 8% ) were 
the type and frequency of events were consistent with those reported in cochlear implantation ( e.g. , electrode open or short circuits , postoperative dizziness , changes in tinnitus ) or other mastoid operations ; no unanticipated adverse events were reported .
fifty events were medical / surgical in nature and included instances of increased tinnitus , vertigo , and other symptoms associated with a mastoidectomy with facial recess approach used in cochlear implantation . it should be noted that the nine adverse events reporting of dizziness , imbalance , and vertigo were likely reported by a few patients and not nine separate patients ; one could have symptoms of dizziness , imbalance , and vertigo .
this trial specified implanting subjects with functional lowfrequency acoustic hearing . unlike prior ci trials ,
this was the first to quantify changes in residual hearing ; any changes in preoperative to postoperative hearing sensitivity were measured throughout the study period .
changes resulting in profound ( > 90 db hl ) hearing loss were reported as anticipated adverse events . at 6months postactivation , 66% of subjects ( 33 of 50 ) retained functional acoustic sensitivity determined by a 5frequency pure tone average ( 125 , 250 , 500 , 750 , 1000 hz ) of a severe degree or better (  90 db hl ) .
the degree of hearing loss and the number of subjects in each hearing loss category and their postintervention outcomes are depicted in figure 2a and b. in addition , the amount of residual hearing and the number of subjects in each category and their postintervention outcomes are depicted in figure 3a and 3b .
subjects with aidable , residual hearing performed better that those without aidable , residual hearing .
however , even if subjects had no residual , aidable hearing , they performed better in the ci electriconly condition than preoperatively with hearing aids .
regarding 17 subjects who did not maintain functional acoustic hearing , five chose to have the hybrid implant explanted and replaced with a standard ci .
improved speech perception of varying degrees was observed compared to that obtained preoperatively with a hearing aid and at the most recent hybrid evaluation prior to revision surgery .
( a ) cnc word scores for subjects with  <  10 , 1020 , 2030 , and  >  30 db of hearing loss at 6 months postcochelar implant activation . the number of subjects in each category of hearing loss is shown .
( b ) azbio + 5 db signaltonoise ratio scores for subjects with  <  10 ,
1020 , 2030 , and  >  30 db of hearing loss at 6 months postcochlear implant activation . the number of subjects in each category of hearing loss is shown .
[ color figure can be viewed in the online issue , which is available at www.laryngoscope.com . ] ( a ) the cnc word scores for subjects in each category of lowfrequency hearing loss .
( b ) the azbio + 5 db signal to noise ratio scores for subjects in each category of lowfrequency hearing loss .
[ color figure can be viewed in the online issue , which is available at www.laryngoscope.com .
apart from cases of profound hearing loss , all but two events ( one sound quality issue and one decreased performance ) were resolved as of database closure .
association of baseline characteristics with adverse events , including profound hearing loss , was examined by univariate cox proportional hazards regression models .
baseline characteristics evaluated included age at implantation , hearing loss duration , severetoprofound hearing loss duration , etiology , and preoperative speech perception .
none were found to be significantly associated with either outcome of an adverse event or profound hearing loss .
results from this study support the conclusion that the nucleus hybrid system ( cochlear ) delivers significantly improved speech understanding in quiet and noise compared to a hearing aid for individuals with bilateral , severe highfrequency hearing loss
. ninety percent of subjects achieved the same or better performance on both speech perception measures when listening with the hybrid system .
when using both ears , all subjects performed equal or better than preoperatively on both measures .
the ssq selfassessment supported speech intelligibility results , with significant improvement on all scales and with greatest improvement on the hearing speech scale . on overall listening satisfaction ,
the number of individuals satisfied increased from 8% preoperatively with amplification to 79% with the hybrid system .
this system delivers important highfrequency information through electrical stimulation and the opportunity to combine it with beneficial lowfrequency residual hearing in one or both ears .
outcomes for five subjects undergoing revision surgery suggest that a standard ci remains a viable treatment when hybrid implantation does not meet expectations .
current hearing aid technology often can not provide audible , clear highfrequency sound for individuals with this type of hearing loss .
individuals with substantial highfrequency losses frequently have nonfunctional inner and outer hair cells ; therefore , amplification can not be effective .
individuals with precipitously sloping losses predictably are frustrated due to significant communication struggles ; they regularly reject amplification , leaving them with no alternative treatments prior to availability of the hybrid system .
limitations to the study include the nonrandomized design , limited sample size , and duration of followup . using subjects as their own control enables clinically meaningful comparisons that account for patient heterogeneity , and use of standardized objective measures of hearing helps ensure validity .
the effect and sample size were large enough to produce statistically significant improvements after 6 months followup ; additional longer term followup for safety and study of the device in larger and diverse subgroups is important .
typically , this is not accessible through amplification for individuals with bilateral severe highfrequency hearing loss and beneficial , aidable lowfrequency hearing .
this system is a new and effective treatment that provides clinically significant improvements in speech understanding through integrated electric and acoustic stimulation in the implanted ear , with additional benefit when listening using both ears  thus fulfilling a need in individuals who to date have had no other treatment options .
 objectives / hypothesisto evaluate the safety and efficacy of acoustic and electric sound processing for individuals with significant residual lowfrequency hearing and severetoprofound highfrequency sensorineural hearing loss.study designprospective , singlearm repeated measures , singlesubject design.methodsfifty individuals ,    18 years old , with lowfrequency hearing and severe highfrequency loss were implanted with the cochlear nucleus hybrid l24 implant at 10 investigational sites . 
 preoperatively , subjects demonstrated consonantnucleusconsonant word scores of 10% through 60% in the ear to be implanted . 
 subjects were assessed prospectively , preoperatively , and postoperatively on coprimary endpoints of consonantnucleusconsonant words , azbio sentences in noise , and selfassessment measures.resultssignificant mean improvements were observed for coprimary endpoints : consonantnucleusconsonant words ( 35.8 percentage points ) and azbio sentences in noise ( 32.0 percentage points ) , both at p  <  0.001 . 
 ninetysix percent of subjects performed equal or better on speech in quiet and 90% in noise . 
 eightytwo percent of subjects showed improved performance on speech in quiet and 74% in noise . 
 selfassessments were positive , corroborating speech perception results.conclusionthe nucleus hybrid system provides significant improvements in speech intelligibility in quiet and noise for individuals with severe highfrequency loss and some lowfrequency hearing . 
 this device expands indications to hearingimpaired individuals who perform poorly with amplification due to bilateral highfrequency hearing loss and who previously were not implant candidates.level of evidence2b . 
 laryngoscope , 126:175181 , 2016 
Level of Evidence
INTRODUCTION
MATERIALS AND METHODS
Objectives and Statistical Analyses
RESULTS
Demographics
Primary Speech Perception Outcomes
Subgroup Results
Bilateral Outcomes
Patient SelfAssessments
Adverse Events
DISCUSSION
CONCLUSION