Clinical Validation of the Lexie Lumen Over the Counter Hearing Aid
Phase: NA
Conditions: Hearing Loss
Sponsor: hearX Group

Effectiveness of an over
-the-counter self -fitting hearing aid 
compared to an audiologist
-fitted hearing aid: A randomized 
clinical trial  
 
 
Trial Protocol and S tatistical  Analysis Plan  
Version: Final (1 February 2022) 
 
Authors: Karina C. De Sousa, Vinaya Manchaiah, Marien A. Graham, David R. 
Moore, De Wet Swanepoel 
 
 
 
Corresponding Author: 
Karina C. De Sousa 
The University of Pretoria 
Department of Speech Language Pathology and Audiology 
karina.swanepoel@up.ac.za 
 
 
 
 
 
 
 
 
 
 
 

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1. Administrative Information 
 
1.1. 
Study identifiers 
 
- 
Research Ethics Approval- University of Pretoria, Humanities Research Ethics 
(Approval Number: HUM07/0322). 
- 
Clinical trial registry- clinicaltrials.gov (Identifier: NCT05337748) 
 
1.2. 
Contributors the protocol and statistical analysis plan 
Name and ORCID ID: 
Primary Affiliation 
Role on the study 
SAP contribution 
 
Karina C. De Sousa 
 https://orcid.org/0000-
0003-1742-1613  
 
University of Pretoria, 
Department of 
Speech-Language 
Pathology and 
Audiology 
 
Primary Investigator 
 
Prepared initial 
draft and statistical 
analyses 
 
Vinaya Manchaiah  
 https://orcid.org/0000-
0002-1254-8407   
 
University of 
Colorado, Anschutz 
Medical Campus 
 
Primary Investigator 
 
Reviewed draft 
and critically 
revised analyses 
plan 
 
Marien Graham 
 https://orcid.org/0000-
0003-4071-9864  
 
 
University of Pretoria, 
Department of 
Science, 
Mathematics and  
Technology 
Education  
 
Study statistician 
 
Reviewed draft 
and critically 
revised statistical 
analyses plan 
 
David R. Moore 
 https://orcid.org/0000-
0002-1567-1945  
 
Cincinnati Children’s 
Hospital Medical 
Center, University of 
Cincinnati 
 
Primary Investigator 
 
Reviewed draft 
 
De Wet Swanepoel 
 https://orcid.org/0000-
0001-8313-1636  
 
University of Pretoria, 
Department of 
Speech-Language 
Pathology and 
Audiology 
 
Primary Investigator 
 
Prepared initial 
draft and revised 
statistical analyses 
plan 
 
 
2. Study site and investigators 
 
2.1. 
Study site 
The study will be conducted at the Department of Speech-Language Pathology and Audiology, 
University of Pretoria, Lynwood Road, Hatfield, Pretoria, Gauteng, South Africa, 0002 
 
Reasons for site selection:  

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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• 
It is a widely recognized research institution in the field of audiology and is the leading 
African research institution in audiology. Furthermore, the site is designated as the 
only official World Health Organization Collaborating Center for the Prevention of 
Deafness and Hearing Loss in Africa. 
• 
In terms of the clinical population served at the university clinic, the racial diversity 
largely reflects the US population in terms of an English-speaking majority white 
population (Census.gov) (1).  78% of participants in this study represented a white only 
adult group compared to 76% in the general US population (Census.gov) (1). 
 
2.2. 
Study investigators and administrative structure 
 
The following individuals will be involved in data collection in the field: 
  
Data collection coordinators and administrative structure 
Role 
Name 
Summary of training experience 
Principal Investigator 
and Research 
Audiologist 
Karina De Sousa, PhD 
Holds the following qualifications: 
• 
Bachelor’s degree in Audiology 
• 
Master’s degree in Audiology 
• 
PhD in audiology 
 
+- 5 years clinical experience 
Research Audiologist 
Rene Mostert 
Holds the following qualifications: 
• 
Bachelor’s degree in Speech Therapy 
and Audiology 
 
+- 20 years practical experience in the UK 
National Health Service 
Research Audiologist 
Nausheen Dawood 
Holds the following qualifications:  
• 
Bachelor’s degree in Audiology 
• 
Master’s degree in Audiology 
 
+- 5 years clinical experience 
 
3. Introduction and study objective 
Hearing loss is a highly prevalent condition, with numerous debilitating consequences when 
left untreated. However, less than 20% of adults with hearing loss in the United States use 
hearing aids. Over-the-counter (OTC) hearing aids became available in October 2022 to 
improve access and affordability. However, clinical effectiveness studies of available OTC 
hearing aids using the existing devices in the market are limited.  The Lexie Lumen hearing 
aid is a wireless self-fitting behind-the-ear hearing aid, coupled with a slimtube and dome, 
intended to amplify sound for individuals 18 years or older with a known or perceived mild to 
moderate hearing impairment. This type of OTC hearing aid functions in conjunction with a 
smartphone app, which allows for an in-situ hearing check to estimate hearing thresholds 
across various audiometric frequencies, and to program the hearing aids using a 
predetermined prescription formula. 
3.1. 
Objective 

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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To compare the clinical effectiveness of a self-fit OTC self-fitting hearing aid (Lexie 
Lumen) with remote support to a gold standard audiologist-fitted hearing. 
3.2.       Research Design and Interventions 
This study will be done using a randomized control trial (RCT), conducted cross-
sectionally (+- 45 days) to evaluate the effectiveness of the self-fit group to an audiologist-
fit group.  
 
3.2.1. SF arm (Intervention group) 
 
In this study, the SF condition means that participants will be provided with the Lexie 
Lumen hearing aids and will be asked to set up and manage the devices using the Lexie 
app, entirely without professional support, as would be standard for this OTC model. 
Hearing aids will be provided in their standard, consumer packaging, including all labelling 
and instructional material. Furthermore, they will be fitted according to the proprietary 
fitting algorithm (Lexie Comfort) using the in-situ thresholds obtained via the Lexie app. 
The fitting algorithm will be based on National Acoustics Laboratories' Non-Linear Version 
2 (NAL-NL2) 1, with additional adjustments aimed for a greater listening comfort.  
 
3.2.2. Audiologist-fit arm (Control) 
 
In the AF condition, participants will be provided with the same Lexie Lumen hearing aids 
fitted to match the National Acoustics Laboratories' Non-Linear Version 2 (NAL-NL2) 
acoustic gain prescriptions as closely as possible 1. AF fitting will be based on diagnostic 
audiometry conducted in a soundproof booth by the audiologist. Diagnostic audiometry 
will follow ISO 8253-1:2010 Acoustics — Audiometric test methods — Part 1: Pure-tone 
air and bone conduction audiometry guidelines2. Participants in the AF group will be 
orientated on the use and management of the hearing aid by the audiologist.  
 
 
Figure 1. Procedural description of the two groups of the randomized controlled trial. SF= self-
fit; AF = audiologist fit. 
 
The study will be conducted as two phases (four visits per participant). Phase I will be 
a two-week, take-home field trial after fitting the hearing aids. During the first 2-weeks 
no assistance or fine-tuning by the online Lexie hearing experts for the SF group will 
be allowed, and no fine-tuning by the audiologist in the AF group. This procedure will 

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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be followed to isolate and only compare the benefit provided by the fitting without the 
help of online support or adjustment.  
 
Phase II will commence at the first follow-up appointment on the third clinical visit. 
During this appointment, participants of the AF group will be allowed to request fine-
tuning or assistance from the audiologist, if desired. The participants in the SF group 
will be informed that assistance could be sought through the Lexie online hearing 
experts, if desired. Phase II will be approximately 6 weeks in duration, and upon 
completion the final clinic visit and assessments will be conducted. Figure 2 provides 
an overview of the study protocol.  
 
 
Figure 2. Trial timeline and design 
 
3.3. 
Sample size 
This study aims to recruit 60 people (approximately 30 people in each group) with parallel 
allocation to the self-fit and audiologist fit groups. Sample size estimation is based on a 
previous OTC trial conducted by Sabin et al. 2020, who recruited similar sample sizes 3. 
3.4. 
Randomization and blinding 
Participants will be randomized into the self-fit or audiologist fit group using a random 
number generator. Due to the nature of the study and requirement for audiologist control 
over the settings in the audiologist-fit group, blinding will not be possible. 
3.5. 
Participant eligibility criteria 
Inclusion: 
• 
Adults >18 years old with a known or self-reported mild to moderate hearing 
impairment. 
• 
Relatively high degree of English proficiency if English is not the participant’s first 
language. This will be measured as per online English proficiency test (EF SET). 
A score of 51% or more, corresponding to an English B2 (upper-intermediate) level 
according to the Common European Framework Reference (CEFR) will be 
included. 
• 
Access to or in possession of a smartphone. 
 
Exclusion: 
• 
History of outer or middle ear disease in the last 90 days.  

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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• 
Audiometric criteria:  
o 
Normal hearing bilaterally (PTA 0.5 to 4 kHz ≤ 20 dB HL) 
o 
Severe hearing loss with any two frequencies at 0.5, 1, 2 and 4 kHz exceeding 
80 dB HL  
o 
Air-bone gaps of more than 20 dB HL at three or more frequencies (0.5 to 4 
kHz) in either ear.  
 
4. Outcome measures 
 
4.1. 
Subjective outcome measures 
Participants will report on overall hearing improvement by means of the following 
standardized questionnaires: 
4.1.1. Abbreviated Profile of Hearing Aid Benefit (APHAB)  
This 
questionnaire 
quantifies 
a 
wearer’s 
self-reported 
difficulty 
with 
communication in everyday communication scenarios (2). Therefore, a 
representative and valid means of measuring the effectiveness of the study 
device.  
Participants will complete this questionnaire unaided at the end of the first visit 
and then again at the end of the first and second field trials. Their responses are 
based on their experience with the study device.  
 
4.1.2. International Inventory for Hearing Aids (IOI-HA)  
Self-report questionnaires such as the IOI-HA determine wearer-oriented 
measures and assess how well a person believes their hearing problems have 
been addressed by means of the benefit derived from their hearing aids (3). 
Participants will complete this questionnaire at the end of the first and second field 
trials. Their responses are based on their experience with the study device. 
 
4.2. 
Behavioral outcome measures 
Participants of both groups will participate in the following speech recognition in noise 
assessments to be conducted as unaided at the pre-field trial stage and as aided at both 
the post-field trials. 
4.2.1. QuickSIN 
Several aspects of the QuickSIN test make it suitable for use in assessing comparable 
improvement of speech-in-noise performance. (1) It is designed to be presented above 
average conversational level (2) It uses a wide range of SNRs, and (3) the multi-talker 
background noise represents a common and challenging communication situation. 
QuickSIN is reported in terms of SNR loss, the increase in SNR required to understand 
speech in noise compared to persons with normal hearing; higher SNR loss indicates a 
poorer outcome (4). 
SNR loss will be measured unaided at the initial assessment for all participants (prior to 
the random allocation process). Twice thereafter the aided SNR Loss will be measured. 
The first aided measurement as per initial fitting settings at the 3rd visit following the post 
2-week field trial for the AF and SF groups. The second SNR loss will be measured with 

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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the hearing aids set to the user’s preferred setting at the 4th visit, post the 6-week field 
trial for both groups.  
4.2.2. Digits-in-Noise 
Since the QuickSIN was developed in American English, one concern was that South 
African participants could have difficulty recognizing the words due to differences in 
dialect. Therefore, in addition to the QuickSIN, speech-in-noise performance will be 
measured using the South African English Digits-in-Noise test (DIN) (5,6). The DIN 
unaided and aided results will be measured following the same procedure as set for 
performing the QuickSIN).  
 
4.3. 
Hypothesis 
 
Primary endpoint hypothesis:  
 
Null hypothesis: No difference in self-reported hearing aid benefit (Abbreviated Profile of 
Hearing Aid Benefit) between the Lexie self-fit group (p0) and audiologist-fit (p1) group at 2- 
and 6-weeks from baseline, i.e., p1 = p0 
 
Alternative Hypothesis (2-sided): The self-reported hearing aid benefit (Abbreviated Profile of 
Hearing Aid Benefit) of the Lexie self-fit group (p1) at 2- and 6- weeks will be non-inferior to 
the audiologist-fit group (p0), within 16.3 (smallest observable change for the APHAB), i.e., p0 
– p1 ≤ 16.3. The non-inferiority margin (-ΔNI) was arbitrarily decided and is defined as the 
degree of hearing benefit (%) change for the smallest observable change on the scales.  
 
Secondary endpoint hypothesis:  
 
Null hypothesis: No difference in self-reported benefit for the Lexie self-fit group (p1) at 2- and 
6-weeks and audiologist fit hearing aids (p0) using the International Outcome Inventory for 
Hearing Aids (IOI-HA), i.e., p1 = p0 
 
Alternative hypothesis (2-sided): The self-reported improvement (IOI-HA) of the Lexie self-fit 
group (p1) at 2- and 6-weeks will be non-inferior to the audiologist fit group, within 1 point on 
all scales (smallest observable difference on each scale). i.e., p0 – p1 ≤ 1. This non-inferiority 
margin (-ΔNI) was decided based on the critical difference score reported for the IOI-HA 4. 
Table 1. Timing of  the assessments 
Visit 
Baseline 
Hearing Aid 
Fitting 
2-week follow-
up 
6-week follow-
up 
Pure tone 
audiometry 
X 
 
 
 
APHAB 
X 
 
X 
X 
IOI-HA 
 
 
X 
X 
QuickSIN 
X 
 
X 
X 
DIN 
X 
 
X 
X 
Real-Ear 
Measurement 
 
X 
 
X 

STATISTICAL ANALYSIS PLAN – EFFECTIVENESS OF AN OVER-THE-COUNTER SELF-FITTING HEARING 
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Null hypothesis: No difference in speech recognition in noise (QuickSIN and DIN) 
improvement between the Lexie self-fit group and audiologist-fit group at 2- and 6- weeks), 
i.e., p1 = p0   
Alternative hypothesis: The improvement of speech recognition in noise for the Lexie self-fit 
group at 2- and 6- weeks will be non-inferior to the audiologist-fit hearing aid using the 
QuickSIN and digits-in-noise test (DIN), within 1.8 dB SNR. The non-inferiority margin (-ΔNI) 
is based on the critical difference score of the QuickSIN 5, i.e., p0 – p1 ≤ 1.8. 
5. Statistical analyses 
 
5.1. Level of statistical significance 
Final analyses of the primary and secondary outcomes will be analysed using a two-sided 
significance level of 5%. 
 
5.2. Statistical software 
 
Analyses will be conducted primarily using the Statistical Packages of the Social Sciences 
(IBM SPSS v28.0).  
 
5.3. Statistical analyses of primary and secondary endpoints 
Patient/ participant characteristics 
Description of the baseline characteristics will be presented by treatment group. Discrete/ 
factor variables will be summarised by frequencies and percentages. Percentages will be 
calculated according to the number of participants for whom data are available. Continuous 
variables will be summarised by using mean and SD, and median and interquartile range 
(Q1-Q3).  
Data that will be gathered include the following: 
• 
Age 
• 
Sex 
• 
Pure tones average (based on audiogram performed by the audiologist) 
• 
Ethnicity 
• 
Level of previous hearing aid experience (Yes/No and duration) 
• 
English proficiency (EF SET English proficiency score) 
• 
Self-perceived degree of hearing loss (mild or moderate) 
Self-reported hearing aid difficulties 
Primary endpoint analyses include the self-reported benefit using the APHAB. Benefit is 
determined by calculating the APHAB scores conducted at the aided assessment (2-week and 
6-week follow-ups) from the baseline scores. The primary endpoint data for all the scores 
measured at all time points (raw scores), along with the calculated benefit scores (unaided-
aided) will be continuous variables. Data will be assessed for normality using the Shapiro 
Wilk’s test. For non-normally distributed variables, non-parametric comparisons between 
groups will be completed using the Mann Whitney U test. For normally distributed variables, 
comparisons will be done using the independent samples t-test. 

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Effect sizes will be calculated for normally distributed variables, where differences were 
significant. Cohen's d is the primary metric for determining effect sizes of normally distributed 
variables, for which the values of 0.8, 0.5 and 0.2 are interpreted as large, medium and small 
effect sizes, respectively. The following formula will be used: 
d = 𝑀1 −𝑀2
𝑆𝐷𝑝𝑜𝑜𝑙𝑒𝑑 
Effect sizes for non-normally distributed variables will be calculated using effect size r for non-
parametric tests, calculated using the following formula: 
𝑧/√𝑁  
IOI-HA (secondary endpoint) will be conducted at 2- and 6-weeks post hearing aid fitting. IOI-
HA data are ordinal response categories and will, therefore, be analysed using non-parametric 
Mann Whitney U tests for comparison between the two groups. 
Behavioral outcome measures 
Speech recognition scores will be conducted at baseline and at the 2- and 6-week follow ups. 
Raw scores will be gathered (continuous variables). Additionally benefit scores will be 
determined by subtracting aided from aided scores. All variables are continuous and will be 
assessed for normality. For non-normally distributed variables, non-parametric comparisons 
between groups will be completed using the Mann Whitney U test. For normally distributed 
variables, comparisons will be done using the independent samples t-test. 
Effect sizes will be calculated for normally distributed variables, where differences were 
significant. Cohen's d is the primary metric for determining effect sizes of normally distributed 
variables, for which the values of 0.8, 0.5 and 0.2 are interpreted as large, medium and small 
effect sizes, respectively. The following formula will be used: 
d = 𝑀1 −𝑀2
𝑆𝐷𝑝𝑜𝑜𝑙𝑒𝑑 
Effect sizes for non-normally distributed variables will be calculated using effect size r for non-
parametric tests, calculated using the following formula: 
𝑧/√𝑁  
Adverse events (Safety analysis) 
Expected SAEs will be summarised as the number and proportion of patients experiencing 
at least one event. This will be done overall and by category. In addition, the total number of 
events will be reported. 
5.4. 
Missing data 
In the event of missing data, analysis will be conducted with no imputation. Cases will be 
removed from analyses and reported. We will check whether the study conclusion changes 
as indicated by the resulting p-values.  
 
 
 

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Keidser G, Dillon H, Carter L, O’Brien A. NAL-NL2 empirical adjustments. Trends in 
amplification. 2012;16(4):211-223.  
2. 
International Standards Organization. Acoustics — Audiometric test methods — Part 1: Pure-
tone air and bone conduction audiometry. ISO-8253-2010. Geneva:ISO2015. 
3. 
Sabin AT, Van Tasell DJ, Rabinowitz B, Dhar S. Validation of a self-fitting method for over-the-
counter hearing aids. Trends in Hearing. 2020;24:2331216519900589.  
4. 
Smith SL, Noe CM, Alexander GC. Evaluation of the International Outcome Inventory for 
Hearing Aids in a veteran sample. Journal of the American Academy of Audiology. 2009;20(06):374-
380.  
5. 
Killion MC, Niquette PA, Gudmundsen GI, Revit LJ, Banerjee S. Development of a quick speech-
in-noise test for measuring signal-to-noise ratio loss in normal-hearing and hearing-impaired listeners. 
The Journal of the Acoustical Society of America. 2004;116(4):2395-2405.