Evaluating the Clinical Effectiveness of a Community-based Hearing Aid Fitting Service Delivery Model Facilitated by Community Healthcare Workers (CHWs) Providing Smartphone-based In-situ and Pre-set Hearing Aid Fittings in Low- and Middle-income Communities (LMICs)

This study aims to establish the effectiveness of community-based hearing aid fittings facilitated by community healthcare workers (CHWs) using mobile health (mHealth) technologies in low- and middle-income communities (LMICs). The investigators hypothesize that amplification offered by smartphone-based in-situ hearing aid (HA) fittings and pre-set hearing aid fittings facilitated by CHWs have superior self-reported outcomes compared to minimal amplification.

To test this hypothesis, the investigators will conduct a single-blind randomized controlled trial (RCT) where participants are assigned to either the experimental smartphone-based in-situ hearing aid fitting, pre-set hearing aid fitting, or minimal amplification fitting. A minimal amplification fitting provides only the most basic level of amplification without individualized adjustments. This level of amplification is primarily intended to prevent occlusion effects rather than to offer meaningful hearing benefits. In this study, a flat 10 dB gain will be provided across frequencies regardless of the degree of hearing loss. A placebo-controlled design is essential for assessing the true effectiveness of hearing aid interventions beyond non-specific effects such as participant expectations or the general experience of wearing a device. Comparing experimental conditions to minimal amplification ensures that any observed benefits are attributable to the intervention rather than psychological or external influences.

Outcomes will be measured by self-reported benefits, with control participants offered the smartphone-based in-situ fitting after six weeks. All participants will also receive a paper-based hearing aid acclimatization and support programme on the day of the hearing aid fitting to assist them in hearing aid use and maintenance. The participants will also be provided a contact number for the CHWs to contact if any assistance is needed.

Rationale Given the limited access to hearing care in LMICs due to prohibitive costs and scarcity of trained professionals, this study leverages mHealth solutions and task-shifting to CHWs as a sustainable and scalable approach. Preliminary studies have shown promising results for the components of these interventions, justifying the need for clinical trials to evaluate their effectiveness. By focusing on end-to-end smartphone-based in-situ hearing aid fittings and acclimatization support, this study aims to create an innovative and accessible model of hearing care that could significantly reduce the global burden of hearing loss.

Additionally, understanding the difference in outcomes between meaningful amplification and minimal amplification is crucial for guiding hearing care strategies in LMICs. If substantial benefits are observed in the experimental groups relative to minimal amplification, it strengthens the case for scaling up CHW-facilitated hearing aid provision as a cost-effective solution. Conversely, if minimal amplification yields similar self-reported outcomes, it may suggest that additional interventions (e.g., counseling, expectations management) are necessary for maximizing hearing aid benefits in these settings.

A randomized, three-arm, single-blind placebo trial (full blinding details below) with 90 participants will be used. The estimated timeline for trial completion is approximately 52 weeks post-hearing aid fitting. The clinical trial will be conducted across three sites (Khayelitsha and Drakenstein Districts in the Western Cape Province of South Africa and Atteridgeville District in the Gauteng Province of South Africa).

Randomization will be conducted before participant enrollment, ensuring that each participant is assigned to one of the three study arms (In-situ fitting, Pre-set fitting, or Minimal Gain fitting) before enrolling in the study.

After baseline assessments to determine candidacy (T0), participants will be randomly assigned and start with one of the three interventions (T1). There will be one placebo-control group with Lexie Lumen hearing aids fitted to minimal gain (i.e., 10 dB HL across the frequency range regardless of hearing loss levels) with two experimental groups: (i) In-situ hearing aid fitting using a proprietary algorithm on Lexie Lumen hearing aids that are based on the National Acoustics Laboratories Non-Linear Version 2 (NAL-NL2) algorithm (ii) Pre-set hearing aid fitting with Go Ultra hearing aids. Following fitting (T1), there will be a 6-week field trial, with follow-up visits scheduled at 6 weeks (T2). Following that, the minimal gain group (control) will be crossed over to in-situ fitting (CG-T2;), and another 6-week field trial will be conducted (follow up at CG-T3). Follow-up visits for the In-situ and Pre-set groups will occur again at 12 weeks (T3), 26 weeks (T4), and 52 weeks (T5).

The primary endpoint will be at the six-week follow-up. The primary outcome measure will be the IOI-HA. A difference of ≥3 points in the IOI-HA score is considered clinically significant based on prior research by Apple, representing a meaningful improvement in hearing aid benefit, satisfaction, and quality of life.

The secondary measures will be the RHHI-S, SNI, and EQ-5D-5L. Baseline RHHI-S, SNI, and EQ-5D-5L scores will be compared with scores obtained at subsequent follow-up visits.

Additionally, a questionnaire with Likert scale questions targeting functional use and meaningful life changes will be completed at all follow-up visits.

Procedure - All assessment and fitting procedures will be facilitated by the CHWs T0: Baseline assessment

• Assess participants for candidacy
• Obtain Informed Consent from the participants
• Record demographic information
• Complete the baseline EQ-5D-5L, SNI, and RHHI-S
• Conduct otoscopy
• Conduct audiometric evaluation to ensure that participants meet the pure tone air-conduction thresholds to be included.
• The clinical research audiologists will then establish candidacy by reviewing the otoscopy and PTA results. The eligible participants will be randomly allocated to either the In-situ, Control, or Pre-set group. Randomization will be conducted before participant enrollment, ensuring that each participant is assigned to one of the three study arms (Lexie Lumen with in-situ fitting, Go Ultra with Pre-set fitting, or Minimal Gain) before enrolling in the study. A random number generator will allocate participant numbers to the respective arms. As soon as a participant is enrolled, they will automatically be assigned to one of the three arms based on the predefined randomization process. This approach ensures unbiased group allocation from the outset of the study. This randomization will be done by an additional independent party.

T1: Hearing-aid fitting Once randomized into one of the three groups, participants will be booked for Visit 2 for hearing aid fitting. All participants will undergo otoscopy, and the participants (not the pre-set group) will undergo an in-situ hearing test via the Lumen hearing aids before the hearing aid fitting.

In-situ Group

• The CHW will fit each participant in the in-situ group with the Lumens programmed using the smartphone-based in-situ (proprietary algorithm based on the NAL-NL2) fitting.
• Participants will select the listening environment they feel most comfortable with.

Control Group

• Participants in the control group will be fitted with Lumens programmed using minimal gain (10 dB gain across frequencies regardless of degree of HL). This will be conducted by the CHW.
• Participants will select the listening environment they feel most comfortable with.

Pre-set Group

● The CHW will fit each participant in the pre-set group with Go Ultra hearing aids on one of the four pre-set programs. Participants will select the program they feel most comfortable with.

T2: Follow-up #1 and cross-over for Control Group

• After 6 weeks of hearing aid use, participants from all groups will return for a follow-up assessment.
• The International Outcome Inventory for Hearing Aids (IOI-HA), the Revised Hearing Handicap Inventory - Screening (RHHI-S), EQ-5D-5L, SNI, and a non-standardized questionnaire will be completed by the participants.
• The control group will then be offered the in-situ intervention (proprietary in-situ fitting based on NAL-NL2).
• An administrative assistant will collect outcome measures to avoid CHW bias.

T3: Follow-up #2 (Final follow-up for Control Group)

• After 12 weeks of hearing aid use, all participants will return for a follow-up assessment.
• The International Outcome Inventory for Hearing Aids (IOI-HA), the Revised Hearing Handicap Inventory - Screening (RHHI-S), EQ-5D-5L, SNI, and a non-standardized questionnaire will be completed by the participants.
• An administrative assistant will collect outcome measures to avoid CHW bias.

T4: Follow-up #3

• After 26 weeks of hearing aid use, only participants from the Experimental groups will return for a follow-up assessment.
• The International Outcome Inventory for Hearing Aids (IOI-HA), the Revised Hearing Handicap Inventory - Screening (RHHI-S), EQ-5D-5L, SNI, and a non-standardized questionnaire will be completed by the participants.
• An administrative assistant will collect outcome measures to avoid CHW bias.

T5: Final Review

• After 52 weeks of hearing aid use, only participants from the Experimental groups will return for a follow-up assessment.
• The International Outcome Inventory for Hearing Aids (IOI-HA), the Revised Hearing Handicap Inventory - Screening (RHHI-S), EQ-5D-5L, SNI, and a non-standardized questionnaire will be completed by the participants.
• An administrative assistant will collect outcome measures to avoid CHW bias.