Benefits From Bimodal Fittings With Cochlear Implant and Hearing Aid vs Bilateral Hearing Aids in Patients With Asymmetric Speech Identification Scores: a Randomised Controlled Trial
Phase: NA
Conditions: Hearing Loss, Cochlear
Sponsor: University of Southern Denmark

1 
 
 
 
A Study Protocol for a Randomised Controlled Trial Evaluating 
the Benefits from Bimodal Solution with Cochlear Implant and 
Hearing Aid vs. Bilateral Hearing Aids in Patients with 
Asymmetric Speech Identification Scores. 
 
 
 
 
 
 
Trial Registration Number: NCT04919928 (ClinicalTrials.gov) 
Updated: 21.08.22 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

2 
 
A Study Protocol for a Randomised Controlled Trial Evaluating 
the Benefits from Bimodal Solution with Cochlear Implant and 
Hearing Aid vs. Bilateral Hearing Aids in Patients with 
Asymmetric Speech Identification Scores. 
 
Yeliz Jakobsen1.2*, Lou-Ann Christensen Andersen3, Jesper Hvass Schmidt1.2 
 
Affiliation 
1 Research Unit for ORL – Head & Neck Surgery and Audiology, Odense University Hospital, 
Odense, Denmark; University of Southern Denmark, Odense, Denmark 
2 OPEN, Odense Patient data Explorative Network, Odense University Hospital, Odense, 
Denmark. 
3Department of Ophthalmology, Lillebaelt Hospital, Vejle Hospital. 
*Correspondence to Dr. Yeliz Jakobsen; Yeliz.jakobsen@rsyd.dk 
Date: Sunday, 21st August 2022 
Version: 3 
 
 
Abstract 
Introduction 
Cochlear implant (CI) and hearing aid (HA) in a bimodal solution (CI + HA) is compared to 
bilateral HAs (HA +HA) to test if the bimodal solution result in better speech intelligibility 
and self-reported quality of life.  
 
Methods and Analysis 
This randomised controlled trial (RCT) is conducted in Odense University Hospital, 
Denmark. Sixty adult bilateral HA users referred for CI surgery is enrolled if eligible and 
undergo: audiometry, speech perception in noise (HINT: Hearing in Noise Test), Speech 
Identification Scores (SIS) and video head impulse test (v-HIT). All participants will receive 
new replacement HAs. After one month they will be randomly assigned (1:1) to the 
intervention group (CI+HA) or to the delayed intervention control group (HA+HA). The 
intervention group (CI+HA) will receive a CI on the ear with a poorer speech recognition 

3 
 
score and continue using the HA on the other ear. The control group (HA+HA) will receive 
a CI after a total of 4 months of bilateral HA use.   
The primary outcome measures are Speech intelligibility measured objectively with HINT 
(sentences in noise) and DANTALE I (words) and subjectively with the Speech, Spatial 
and Qualities of Hearing scale questionnaire (SSQ-12). Secondary outcomes are patient 
reported Health-Related Quality of Life (HRQoL) scores assessed with the Nijmegen 
Cochlear Implant Questionnaire (NCIQ), the Tinnitus Handicap Inventory (THI) and 
Dizziness Handicap Inventory (DHI). Third outcome is listening effort assessed with pupil 
dilation during HINT 
In conclusion, the purpose is to improve clinical decision-making for CI candidacy and 
optimize bimodal solutions.  
 
Ethics and Dissemination  
This study protocol was approved by the Ethics Committee Southern Denmark project ID 
S-20200074G. All participants are required to sign an informed consent form. 
This study will be published upon completion in a peer-reviewed publications and scientific 
conferences. 
 
Trial Registration Number: NCT04919928 (ClinicalTrials.gov) 
 
 
 
 
 

4 
 
Strengths and Limitations of This Study  
• The study uses comprehensive measures of self-reported outcomes as well as 
objective tests of speech intelligibility.   
• Listening effort controlled with pupillometry during objective tests of speech 
intelligibility. 
• Open label RCT (blinding is not possible due to visibility of the CI). 
• Possible large drop rates if new HAs improve speech intelligibility to an extent that 
CI treatment is rejected or postponed.   
 
Introduction 
Background 
Cochlear implants (CIs) have been used to restore hearing in individuals with severe to 
profound sensorineural hearing loss. Initially, most patients receiving a cochlear implant 
were profoundly deaf in both ears. (1, 2) However, recently it has become more common to 
implant patients with significant residual hearing in the affected ear, as well as in patients 
with asymmetric hearing loss and single-sided deafness, with significant residual hearing or 
normal hearing on the contralateral side.(3, 4) A CI in one ear and a HA in the other ear can 
provide enhanced hearing performance in patients with asymmetrical hearing.(5, 6) The 
combination of CI and HA is referred to as bimodal hearing or bimodal solution.(7) 
 
CI Candidacy 
In the UK, The National Institute for Health and Care Excellence (NICE) have listed 
guidelines for cochlear implantation and recommends that unilateral CI is offered to patients 

5 
 
with severe to profound deafness who do not receive adequate benefit from acoustic hearing 
aids. Severe to profound deafness is defined as pure-tone audiometric threshold ≥ 80 dB HL 
at 2 or more frequencies (500 Hz, 1,000 Hz, 2,000 Hz, 3,000 Hz and 4,000 Hz). Another 
criteria is that SIS< 50% in the ear considered for implantation and in best aided condition 
SIS≤60%(8).  
The Danish CI candidacy criteria consists of SIS (without HAs, measured with 
headphones) ≤45% and a SIS ≤65% (in best aided condition) in the ear considered for 
implantation using DANTALE I monosyllabic word-lists.(9)  Additional testing to evaluate 
speech understanding is assessed by HINT.(10, 11) 
The recommendation for a CI might be less clear for patients with asymmetric hearing 
because they may not fall into the traditional referral criteria but would likely benefit from a 
CI. It is therefore necessary to establish more evidence to support the effectiveness of 
bimodal CI+HA versus HAs in patients with asymmetric hearing.   
 
Bimodal Solution vs. Bilateral HAs 
Normal hearing listeners (NH) benefit from listening with two ears, which help them 
understand speech in noise and identify sound location.  
Benefits from listening with two ears include: head shadow effect, binaural summation, 
binaural squelch, localization and spatial release from masking.(12-15) 
Patients with hearing loss often do not have these benefits, and they are often not accessible 
to CI patients. (15)Many bimodal CI and HA users are missing these benefits because the 
devices are unsynchronized.(16) 
Until now it is unknown when to introduce the bimodal solution and making sure that 
patients are well-fitted with hearing aids when they are given the candidacy assessment.  

6 
 
The question is if the bimodal benefits are bigger than the bilateral hearing aid condition 
when they are well fitted? 
This study will therefore support and strengthen the preoperative clinical decision to 
recommend a bimodal solution with a CI and a HA versus the continuous use of bilateral 
HAs. This may offer the patient faster and more effective treatment because delaying the 
surgery may not be beneficial.  
 
Patient-Reported Outcome Measures 
Benefits of the CI are measured subjectively with Patient-Reported Outcome Measures 
(PROMs) as SSQ12, NCIQ, THI and DHI.(17-24)   
 
The validity and reproducibility of the Danish version of THI has been reported(24). 
SSQ12, DHI, NCIQ have all been translated into Danish and backward translated to 
English following a cultural adaption and pilot-testing to ensure correct understanding of 
the questionnaires. Test-retest reliability has been assessed as well.(18, 20, 22)  
 
Listening Effort 
Patients with CI often experience high levels of listening effort, they often report that 
understanding speech causes high levels of increased sustained effort which results in 
feelings of fatigue.(25) These feelings may lead patients to withdraw socially due to the 
stresses involved in communication even though they may not specifically report 
difficulties with speech understanding.(19)  
Effort in listeners with NH can be reflected by the relationship between speech intelligibility 
and pupil-dilation.(26) Listening effort has been defined as the “Deliberate  allocation of 

7 
 
mental resources to overcome obstacles in goal pursuit when carrying out a task” and is 
the basis for the Framework for Understanding Effortful Listening (FUEL) model.(27)  
Understanding speech in challenging hearing environments results in increased auditory 
and cognitive processing which can be observed objectively by measuring the pupil 
dilation during speech perception in noise, in a task such as the HINT(28-30)  
 
Rationale and Objectives 
This randomised controlled trial is designed to improve clinical decision-making for CI 
candidacy for patients with asymmetric hearing. It is necessary to establish more evidence 
to support the effectiveness and the fitting optimization of bimodal CI+HA versus HAs in 
patients with asymmetric hearing.   
The first objective of the study is to evaluate the subjective (SSQ12) and objective 
(Hearing In Noise Test (HINT) which is word and sentence based and DANTALE I, which 
is monosyllabic word-based) benefits of a bimodal solution (CI+HA) compared to 
(HA+HA).  
The second objective is to compare and evaluate patient self-reported outcomes with 
NCIQ, THI and DHI in the intervention group (CI+HA) with the control group (HA+HA). 
The third objective is to evaluate if listening effort, hypothesized to cause fatigue, can be 
measured objectively by HINT with pupillometry.  
To minimize listening effort and optimize the fitting of bimodal solution the CI fitting and 
loudness balancing on individual level will be evaluated.(2, 31, 32)  
 
 
Methods and Analysis  

8 
 
Study Design, Ethics and Registration 
This study is a prospective randomised controlled trial based on a single centre conducted 
in Odense University Hospital, Denmark. The study started 01/02/2022 and is expected to 
end 30/07/2024.  It was successfully registered at ClinicalTrials.gov with registration 
number: NCT04919928. 
This study has been approved at Research Ethics Committee Southern Denmark (Projekt-
ID: S-20200074G) 21st August 2020 to 31st December 2024. 
 
Study Population 
Sixty participants with bilateral hearing-loss and asymmetric speech identification scores 
referred for CI surgery  will be included (Figure 1).  
 
Inclusion Criteria 
• Adults >18 years old. 
• Fluent in Danish, including reading and writing 
• Acquired post-lingual deafness  
• Use of bilateral HAs for at least one year prior to evaluation for cochlear implantation 
candidacy. This to ensure, that both ears have received auditive stimulation 
• PTA > 40 dB HL in the ear considered for CI implantation and PTA≥40 and ≤ 70dB 
HL in the contralateral ear in best aided condition, in quiet and in noise and in free 
field. 

9 
 
• SIS <70% in best aided condition in the ear considered for CI implantation and SIS 
≥30% and ≤70% in best aided condition in the contralateral ear, in quiet and in noise 
and in free field. 
Exclusion Criteria 
• Vestibular loss in the ear not considered for CI implantation  
• Surgical issues interfering with the site of implantation or anatomical 
contraindications such as cochlear malformations, which will be determined using 
MRI or CT-scans. 
• Auditory nerve lesions. 
• Central auditory pathway pathologies. 
• Otosclerosis. 
• Single sided deafness (SSD). 
 
Setup 
A timeline of the study is shown in (Figure 2). 
All enrolled participants will be tested with audiometry and v-HIT to determine hearing 
thresholds and status of balance function during the first visit.  Patients will receive new 
replacement HAs. These HAs will be fitted during the second visit and if necessary refitted 
at every visit in the clinic throughout the study. The baseline measurements will be 
conducted when both groups have used the new replacement HAs to ensure 
acclimatisation. The measurements are SIS in quiet and in noise with a signal-to-noise ratio 
(SNR) of 0dB using DANTALE I speech material. The speech and masking white noise 

10 
 
stimulus will be presented at 65 dB SPL in the free field. Stimuli will be presented as auditory 
stimuli only as well as with visual cues, the latter to allow participants to use lipreading cues.  
Pupillometry variables are Peak Pupil Dilation (PPD), Mean Pupil Dilation (MPD), peak-
time and standard deviation using HINT (sentences and words).  
The HINT sentences are presented at a speech level of 65dB and initially an adaptive 
SNR is used to identify the SNR of 70% correct word recognition. The SNR at 70% correct 
word recognition is used as a fixed SNR during HINT test. The noise is multi-talker babble 
noise, in free field, tested in best aided condition. The pupillometry glasses is the Oticon 
Medical Pupil Labs glasses.  
 
Recruitment, Stratification, Randomisation and Allocation 
All eligible participants will sign a written, informed consent in clinic after receiving verbal 
and written study information in Danish. The Danish consent form is available online at the 
Odense University Hospital Research Unit website.(33) 
To ensure acclimatisation, participants will receive new replacement HAs fitted with the 
National Acoustic Laboratories (NAL) -non-linear (NL)2 fitting algorithm one month before 
the experiment.  
They will then undergo stratification, depending on the hearing thresholds. One group will 
consist of participants with PTA ≥ 70dB HL; and the other group will consist of subjects 
with PTA ≤ 70dB HL and ≥ 40 dB HL according to the inclusion criteria. The reason for this 
stratification is because pre-operative hearing thresholds may affect the measured 
outcomes in the study. Stratification ensures that both the intervention group and the 
control group will have an equal distribution of patients with profound hearing loss on the 
ear considered for implantation.  

11 
 
 
Then the participants will be randomly allocated into two groups: the intervention group 
(CI+HA) and the control group (HA+HA) according to 1:1 ratio using a blocked 
randomisation with randomly varying block size (4 or 6). 
This randomisation will be accomplished using a computer-generated random sequence in 
Research Electronic Data Capture (REDCap), hosted by Odense Patient Explorative 
Network (OPEN) in the Region of Southern Denmark and developed by Vanderbilt 
University, Nashville, Tennessee, United States.(34) 
REDCap will also be used to send out the questionnaires to the participants´ online 
mailbox (called Eboks in Denmark) throughout the study (see timeline (Figure 2)) and 
automatically save the data.  
Participants will have the opportunity to return to their original HAs if they prefer to do so 
after one-month of acclimatisation.  
 
Control Group 
Thirty patients, who will be age-matched, randomised and allocated to the control group 
HA+HA will continue the use of the new replacement HAs for another three months (total 
four months of new replacement HA+HA use), serving as the delayed intervention control 
group.  
 
Intervention Group  
Thirty patients, who will be age-matched, randomised and allocated to the intervention 
group CI+HA will undergo surgery as soon as possible after the HA acclimatisation period.  
 

12 
 
 
HA Fitting 
The participant will receive either Phonak (Phonak Link M) or GN (ReSound LiNX Quattro 
or Resound ENZO Q) based on their personal preference. Both these HA models can be 
fitted with a CI by Advanced Bionics and Cochlear, respectively.  
The HAs will be fitted according to NAL-NL2 procedures prescriptive fitting formula, which 
optimizes audibility in the bimodal solution(2) and will be verified with REM (Real Ear 
Measurement) to ensure that the HA is providing adequate gain and then further adjusted 
for comfort based on patient feedback.(35)  
The new HAs will be prescribed to the patients free of charge and future service will also 
be free of charge. 
Participants can drop out of the study if they do not want CI surgery. Collected data will be 
analysed if the patient still consents. 
 
CI fitting  
The CI will be selected depending on the participant´s HA selection; that is, the CI that is 
compatible with the HA will be selected in order to ensure the most optimal bimodal fitting. 
One-month post-surgery, the CI will be activated according to the settings and stimulation 
strategy based on patient´s feedback. The CI will then be fitted with the HA according to 
the bimodal fitting formula allowing the HA to keep the NAL-NL2 fitting along with the 
wireless connection with the CI. (36, 37) 
Patients hearing thresholds will be tested on CI activation day. The residual hearing will 
not be stimulated in this study. 
 

13 
 
All participants are offered standard rehabilitation with a speech therapist, including three 
visits a week up to 10 weeks following the initial fitting.  
The training focuses on learning to identify different sounds from the environment and word 
discrimination. 
The new CI will also be prescribed to the patients free of charge and future service will be 
free of charge as well. 
 
Loudness Balancing 
At 3- months follow-up the post-surgery complications will be evaluated and the levels in 
the CI will be adjusted if necessary.  
In the loudness balancing procedure, the patient will have both the hearing aid and CI 
activated and at the 6-month follow-up, when the CI mapping levels are stable, patients will 
be randomised and assigned to one of three bimodal fitting groups: 
Group A) will not complete any specific loudness balancing procedures, CI and HA will be 
fitted based on individual feedback from the patient.  
Group B) will be fitted/finetuned using a bimodal loudness balancing task at a medium 
input level and adjusted based on the patient feedback. The audiologist will present a mid-
level sound (approx. 55dB SPL (sound pressure level)) at the center-speaker.  
 Group C) will be fitted/finetuned using a bimodal loudness balancing task as group B but 
the audiologist will play three levels and adjust the gain for three input levels (soft, 
medium, and loud) according to the patient feedback.  
For both groups B and C, the patient will be given a ‘Bimodal Fusion’ illustration (see Figure 
3) and asked to provide feedback about the location of the sound by tracing over the line of 

14 
 
the head. The HA gain will be adjusted using the bimodal adjustment option until the patient 
reports that the sounds are perceived at the center of the head.(24)  
 
Primary Outcome 
Primary outcomes are Speech intelligibility scores measured objectively with HINT 
(sentences and words) and DANTALE I and subjectively with Speech, Spatial and 
Qualities of Hearing scale (SSQ-12). (9, 10, 22) 
 
Secondary Outcome 
Patient reported outcomes scores assessed with the Nijmegen Cochlear Implant 
Questionnaire (NCIQ), The Tinnitus Handicap Inventory (THI) and Dizziness Handicap 
Inventory (DHI). (18, 20, 24) 
 
Third Outcome 
Listening effort assessed with pupil dilation with HINT.(10) 
 
Statistics 
Power calculation 
Power calculations with a power of 0.8 with a significance level of 0.05 have been made 
with STATA IC-15 using standard deviations for the HINT test and expected effect size (38) 
the NCIQ(18), and the SSQ (internal communication with BEAR (Better Hearing 
Rehabilitation) study on hearing aid use in Denmark) (Table 1). An estimated within 
participant standard deviation from the BEAR study of 1,9 in an HA population using the 

15 
 
SSQ-12 is used to calculate the sample size. A difference of 1,4 will require 30 participants 
in each arm. The effect size is expected to be larger in the CI group which will lower the 
number of required subjects even further. 
Based on this, 30 participants must be enrolled in each arm. Additional six patients (20%) 
in each arm will be enrolled in the study to account for dropouts. 
 
Table 1: Power calculations for the desired tests. Estimated within participant standard deviations (SD pre and SD post) with expected 
difference and the calculated required group size. 
 
Definition of Analysis Sets 
Strategy for intention to treat analysis with incomplete observations.(39) 
1. Attempt to follow-up on all randomised participants, even if they withdraw from 
allocated treatment. 
2. Perform a main analysis of all observed data that are valid under a plausible 
assumption about the missing data. 
3. Perform sensitivity analyses to explore the effect of deviations from the assumption 
made in the main analysis. 
4. Account for all randomised participants, at least in the sensitivity analyses. 
 
Test 
SD pre 
SD post 
Expected 
difference between 
the two treatment 
arms 
Minimum 
required group 
size 
1. HINT 
6.3% 
6.3% 
5% 
26 
2. NCIQ – basic sound perception 
14.4 
23.5 
53 
4 
2. NCIQ 
13.4 
19.6 
34 
6 
2. NCIQ – speech perception 
18.8 
17.8 
17 
20 
2.NCIQ Self-esteem 
20.1 
16.4 
22 
13 
2.NCIQ Activity 
23.0 
15.9 
27 
10 
2.NCIQ Social Interactions 
19.8 
14.5 
25 
9 
3. SSQ Total 
1.9 
1.9 
1.4 
30 

16 
 
Analysis specification 
A constrained linear mixed model is used to analyse the outcome. 
The model will include randomisation group (CI+HA / HA+HA) and time (baseline/follow-up) 
and their interaction as fixed effects along with the threshold strata that were used in 
stratifying the randomisation. The model is constrained so that the mean at baseline agrees 
across the two treatment groups adjusted for threshold stratum, which is reasonable due to 
the randomisation of implant fitting. Patient ID will be included as a random effect to account 
for the repeated measurements.  
Secondary outcomes will be analysed analogously in a constrained linear mixed model 
adjusting for randomisation strata. Model validation checks will be undertaken as described 
above, switching to bootstrapping the standard errors when model assumptions are 
rejected. 
Covariates such as age and gender will be included in all models. 
 
Sensitivity analysis  
Inclusion is performed conditional on Pure Tone Average (PTA) (from 0.5 to 4 kHz) PTA  > 
40 dB HL and SIS <50% in the ear considered for CI implantation and <70% in the best-
aided condition  which may lead to a truncation effect in the distribution of baseline 
measurements. To address this, an analysis of covariance (ANCOVA) model conditioning 
on the baseline will be used to obtain a sensitivity analysis estimate for the main 
outcome.(40) 
The statistical analysis plan is attached as “supplementary file” along with the Data 
Description listed in Appendix A. 

17 
 
 
Patient and Public Involvement 
A focus-group interview was established with six cochlear implant patients. The patients 
commented on their decision to transition from HA to CI. Based on the feedback from the 
focus group, the research questions were developed.  
The patients also reported problems with adjustments of the CI, when meeting the 
audiologist for CI adjustment controls.   
 
Ethics and Dissemination  
Ethics approval for the conduct of this study was obtained from the Ethics Committee 
Southern Denmark, 21st August 2020 project ID S-20200074G. 
The project is approved by the Danish Data Protection Agency (file no. 20/22868) in 
Region South Denmark.  
All participants are treated according to current clinical standards regardless of the 
randomised study participation. The participants are volunteers and can at any moment 
withdraw their participation in the study without affecting their current or future treatment 
rights.  
The Informed Consent form will be found online as an online supplementary file and it will 
be signed by all participants willing to participate the study and stored in their electronic 
journals in Department of Audiology, Odense University Hospital. All patients are given both 
oral and written information about the study. 
 
 

18 
 
 
Results 
Results will be presented at national and international congresses and published in the 
scientific literature for the attention of professional and scientific audiences on behalf of all 
study sites and collaborators. A lay summary report will be published for patients and 
members of the public. 
 
Footnotes 
Authors’ Contributions:  
YJ and JHS are involved in the conception of the study. LCA and JHS wrote the grant application. LCA and JHS wrote the 
draft of the manuscript. JHS designed and revised the draft of the methodological content. YJ reviewed and JHS critiqued 
the manuscript. YJ and JHS approved the final manuscript6 
Funding:   
This study is funded by William Demant Foundation grant no. 19-3470 and Interfond grant no. 33.188 
Competing Interests:  
None declared 
Contributorship Statement/Acknowledgements:  
We are very thankful of the academic English editing of Ph.D. Kathleen F. Faulkner and Assistant Professor Lindsey Van 
Yper 
We are grateful for the contribution from the patient advisers. 
Protocol and Registration: 
This study is registered in ClinicalTrials.gov: NCT04919928 
 
 
Reference List 
 
1. 
Morera C, Manrique M, Ramos A, Garcia-Ibanez L, Cavalle L, Huarte A, et al. 
Advantages of binaural hearing provided through bimodal stimulation via a cochlear implant 
and a conventional hearing aid: a 6-month comparative study. Acta Otolaryngol. 
2005;125(6):596-606. 

19 
 
2. 
Vroegop JL, Goedegebure A, van der Schroeff MP. How to Optimally Fit a Hearing 
Aid for Bimodal Cochlear Implant Users: A Systematic Review. Ear Hear. 2018;39(6):1039-45. 
3. 
Firszt JB, Holden LK, Reeder RM, Cowdrey L, King S. Cochlear implantation in 
adults with asymmetric hearing loss. Ear Hear. 2012;33(4):521-33. 
4. 
van Zon A, Peters JP, Stegeman I, Smit AL, Grolman W. Cochlear implantation for 
patients with single-sided deafness or asymmetrical hearing loss: a systematic review of the 
evidence. Otol Neurotol. 2015;36(2):209-19. 
5. 
Thompson NJ, Dillon MT, Buss E, Rooth MA, King ER, Bucker AL, et al. Subjective 
Benefits of Bimodal Listening in Cochlear Implant Recipients with Asymmetric Hearing Loss. 
Otolaryngol Head Neck Surg. 2020;162(6):933-41. 
6. 
Dillon MT, Buss E, Rooth MA, King ER, McCarthy SA, Bucker AL, et al. Cochlear 
Implantation in Cases of Asymmetric Hearing Loss: Subjective Benefit, Word Recognition, and 
Spatial Hearing. Trends Hear. 2020;24:2331216520945524. 
7. 
van Loon MC, Smits C, Smit CF, Hensen EF, Merkus P. Cochlear Implantation in 
Adults With Asymmetric Hearing Loss: Benefits of Bimodal Stimulation. Otol Neurotol. 
2017;38(6):e100-e6. 
8. 
The National Institute for Health and Care Excellence (NICE) 2019. 
9. 
Elberling C, Ludvigsen C, Lyregaard PE. DANTALE: a new Danish speech material. 
Scand Audiol. 1989;18(3):169-75. 
10. 
Nielsen JB, Dau T. The Danish hearing in noise test. Int J Audiol. 2011;50(3):202-8. 
11. 
Zhang E, Coelho DH. Beyond Sentence Recognition in Quiet for Older Adults: 
Implications for Cochlear Implant Candidacy. Otol Neurotol. 2018;39(8):979-86. 
12. 
Bronkhorst AW, Plomp R. The effect of head-induced interaural time and level 
differences on speech intelligibility in noise. J Acoust Soc Am. 1988;83(4):1508-16. 
13. 
Bronkhorst AW, Plomp R. Binaural speech intelligibility in noise for hearing-
impaired listeners. J Acoust Soc Am. 1989;86(4):1374-83. 
14. 
Bronkhorst AW, Plomp R. A clinical test for the assessment of binaural speech 
perception in noise. Audiology. 1990;29(5):275-85. 
15. 
Choi SJ, Lee JB, Bahng J, Lee WK, Park CH, Kim HJ, et al. Effect of low frequency on 
speech performance with bimodal hearing in bilateral severe hearing loss. Laryngoscope. 
2016;126(12):2817-22. 
16. 
Balkenhol T, Wallhäusser-Franke E, Rotter N, Servais JJ. Cochlear Implant and 
Hearing Aid: Objective Measures of Binaural Benefit. Front Neurosci. 2020;14:586119. 
17. 
Devlin NJ AJ. Getting  the most of proms: putting health outcomes at the heart of 
NHS decision-making. London, Kings Fund and Office of Health Economics 2010. 
18. 
Hinderink JB, Krabbe PF, Van Den Broek P. Development and application of a 
health-related quality-of-life instrument for adults with cochlear implants: the Nijmegen 
cochlear implant questionnaire. Otolaryngol Head Neck Surg. 2000;123(6):756-65. 
19. 
Hughes SE, Hutchings HA, Rapport FL, McMahon CM, Boisvert I. Social 
Connectedness and Perceived Listening Effort in Adult Cochlear Implant Users: A Grounded 
Theory to Establish Content Validity for a New Patient-Reported Outcome Measure. Ear Hear. 
2018;39(5):922-34. 
20. 
Jacobson GP, Newman CW. The development of the Dizziness Handicap Inventory. 
Arch Otolaryngol Head Neck Surg. 1990;116(4):424-7. 
21. 
Mertens G, De Bodt M, Van de Heyning P. Cochlear implantation as a long-term 
treatment for ipsilateral incapacitating tinnitus in subjects with unilateral hearing loss up to 10 
years. Hear Res. 2016;331:1-6. 

20 
 
22. 
Noble W, Jensen NS, Naylor G, Bhullar N, Akeroyd MA. A short form of the Speech, 
Spatial and Qualities of Hearing scale suitable for clinical use: the SSQ12. Int J Audiol. 
2013;52(6):409-12. 
23. 
Servais JJ, Hörmann K, Wallhäusser-Franke E. Unilateral Cochlear Implantation 
Reduces Tinnitus Loudness in Bimodal Hearing: A Prospective Study. Front Neurol. 2017;8:60. 
24. 
Zachariae R, Mirz F, Johansen LV, Andersen SE, Bjerring P, Pedersen CB. Reliability 
and validity of a Danish adaptation of the Tinnitus Handicap Inventory. Scand Audiol. 
2000;29(1):37-43. 
25. 
Winn MB, Edwards JR, Litovsky RY. The Impact of Auditory Spectral Resolution on 
Listening Effort Revealed by Pupil Dilation. Ear Hear. 2015;36(4):e153-65. 
26. 
Zekveld AA, Kramer SE, Festen JM. Pupil response as an indication of effortful 
listening: the influence of sentence intelligibility. Ear Hear. 2010;31(4):480-90. 
27. 
Pichora-Fuller MK, Kramer SE, Eckert MA, Edwards B, Hornsby BW, Humes LE, et 
al. Hearing Impairment and Cognitive Energy: The Framework for Understanding Effortful 
Listening (FUEL). Ear Hear. 2016;37 Suppl 1:5s-27s. 
28. 
Ohlenforst B, Zekveld AA, Lunner T, Wendt D, Naylor G, Wang Y, et al. Impact of 
stimulus-related factors and hearing impairment on listening effort as indicated by pupil 
dilation. Hear Res. 2017;351:68-79. 
29. 
Wendt D, Koelewijn T, Książek P, Kramer SE, Lunner T. Toward a more 
comprehensive understanding of the impact of masker type and signal-to-noise ratio on the 
pupillary response while performing a speech-in-noise test. Hear Res. 2018;369:67-78. 
30. 
Eckert MA, Teubner-Rhodes S, Vaden KI, Jr. Is Listening in Noise Worth It? The 
Neurobiology of Speech Recognition in Challenging Listening Conditions. Ear Hear. 2016;37 
Suppl 1(Suppl 1):101s-10s. 
31. 
Francart T, McDermott HJ. Psychophysics, fitting, and signal processing for 
combined hearing aid and cochlear implant stimulation. Ear Hear. 2013;34(6):685-700. 
32. 
Wang Y, Naylor G, Kramer SE, Zekveld AA, Wendt D, Ohlenforst B, et al. Relations 
Between Self-Reported Daily-Life Fatigue, Hearing Status, and Pupil Dilation During a Speech 
Perception in Noise Task. Ear Hear. 2018;39(3):573-82. 
33. 
Jakobsen Y, Schmidt JH. Behandling af nedsat hørelse med cochlear implantat (CI) 
og høreapparat i kombination i forhold til høreapparater alene. 2022. 
https://ouh.dk/media/vwihy4wi/deltagerinformation-for-bimodal-med-
lodtr%C3%A6kning.pdf (accessed 21. Aug. 2022). 
34. 
Harris PA, Taylor R, Thielke R, Payne J, Gonzalez N, Conde JG. Research electronic 
data capture (REDCap)--a metadata-driven methodology and workflow process for providing 
translational research informatics support. J Biomed Inform. 2009;42(2):377-81. 
35. 
Digeser FM, Engler M, Hoppe U. Comparison of bimodal benefit for the use of DSL 
v5.0 and NAL-NL2 in cochlear implant listeners. Int J Audiol. 2020;59(5):383-91. 
36. 
Cuda D, Murri A, Mainardi A, Chalupper J. Effectiveness and efficiency of a 
dedicated bimodal fitting formula. Audiol Res. 2019;9(1):219. 
37. 
Stronks HC, Briaire JJ, Frijns JHM. The Temporal Fine Structure of Background 
Noise Determines the Benefit of Bimodal Hearing for Recognizing Speech. J Assoc Res 
Otolaryngol. 2020;21(6):527-44. 
38. 
Poissant SF, Bero EM, Busekroos L, Shao W. Determining cochlear implant users' 
true noise tolerance: use of speech reception threshold in noise testing. Otol Neurotol. 
2014;35(3):414-20. 

21 
 
39. 
White IR, Horton NJ, Carpenter J, Pocock SJ. Strategy for intention to treat analysis 
in randomised trials with missing outcome data. Bmj. 2011;342:d40. 
40. 
Liu GF, Lu K, Mogg R, Mallick M, Mehrotra DV. Should baseline be a covariate or 
dependent variable in analyses of change from baseline in clinical trials? Stat Med. 
2009;28(20):2509-30.