Setting {9}
In-clinic appointments will take place at the University of Auckland Hearing and Tinnitus Clinic or in a private audiology clinic in the Auckland region. Remote appointments will connect to the home of each participant (or a location of their preference). Participants will be asked to choose a quiet location where they were unlikely to be interrupted for the duration of the appointment.
Eligibility criteria {10}
People eligible for the study must comply with all of the following at time of enrolment:
- Diagnosed sensorineural hearing loss between slight and moderate, according to WHO definitions, with thresholds unchanged within ±10dB over the past twelve months. Participants with complex hearing needs (tinnitus, single-sided deafness, conductive loss greater than 15dB) are excluded from this study;
- At least one years’ experience as a hearing aid wearer. Experienced hearing aid users are familiar with the basic functions of hearing aids (switching on and off, insertion and removal) required for remote fitting services. Experienced hearing aid users have higher and more stable sound output requirements than new hearing aid users;
- Access to a compatible smartphone or tablet with connection to the internet in a suitably private location (min 5Mbs upload/download speed). Participants will be given the use of an appropriate smartphone if they do not have a compatible one themselves.
- Available for the duration of the study and to attend in-clinic appointments.
Who will take informed consent? {26a}
Informed consent will be obtained by trained clinical research assistants and/or a clinician at the start of the first appointment and before any data is collected.
Additional consent provisions for collection and use of participant data and biological specimens {26b}
Not applicable. No biological specimens will be collected.
Interventions
Explanation for the choice of comparators {6b}
In-clinic hearing aid programming with real-ear verification is the current gold standard for audiology in New Zealand and many other countries. Remote hearing aid fitting provides a useful alternative, providing clinical outcomes are equal. The intervention protocols have been developed to replicate real-world processes in order to identify any clinically significant differences.
Intervention description {11a}
The study flow is presented in Figure 1. Interested participants will be contacted to discuss the study, go through the Participant Information Sheet, answer questions and schedule the first appointment. Consent will be obtained at the start of the first appointment and before any data is collected.
Participants will complete a standard audiometry test battery (pure-tone audiometry for air- and bone-conduction thresholds, speech audiometry, and immittance audiometry) in accordance with the New Zealand Audiological Society Best Practice Guidelines (24-26)) in order to confirm study selection criteria are met and to ensure accurate hearing aid prescription.
Participants will have two hearing aid fittings: an in-clinic hearing aid fitting with real-ear verification and a remote hearing aid fitting with subjective verification.
Participants will be given the opportunity to go into a prize draw in acknowledgement and thanks for their time and participation in the study. While the hearing aids used in the study will be returned at the conclusion of the study, participants will have the opportunity to privately purchase new hearing aids of the same model and performance if they would like to do so.
Initial In-Clinic Hearing Aid Fitting
For the initial in-clinic hearing aid fitting, participants will be fit binaurally with premium-level, rechargeable, receiver-in-the-canal hearing aids. The receiver and dome configuration will be chosen using standard clinical procedures and be consistent for each participant for the duration of the study. The hearing aids will be programmed through the manufacturer’s software to 100% acclimatisation using the National Acoustics Laboratory Non-Linear 2 (NAL-NL2) prescription targets for long-term hearing aid wearers.
REAR will be verified using a Natus Aurical Freefit and Otometrics Otosuite PMM module, with the gain settings adjusted through hearing aid software to meet NAL-NL2 targets for soft (55dB), medium (65dB) and loud (75dB) stimuli using the International Speech Test Signal. On-ear measurement of maximum power output will be measured at 85dB to ensure estimated uncomfortable loudness levels are not exceeded.
Where hearing aid programming features are available for an in-clinic session but are not available for a remote session, these will be removed from the in-clinic fitting protocol to maintain blinding for the clinicians performing the follow-up appointments.
Hearing aid settings will be optimised using subjective participant feedback to balance overall volume, perceived sound quality, and perception of own voice/occlusion. This process will follow an interview-style approach, with the participant asked to comment on each component and the clinician making small adjustments to the hearing aid settings until the participant is satisfied with the sound. The hearing aid setting will then be stored and the hearing aids retained at the clinic.
Participants will be required to have an app installed on their smartphone or tablet before the remote hearing aid fitting appointment. They will be guided through this process at the end of the initial in-clinic fitting appointment.
Initial Remote Hearing Aid Fitting
Approximately two weeks after the in-clinic hearing aid fitting, a remote hearing aid fitting appointment will take place. The time interval is to allow participants’ memory of the sound of the in-clinic programming to decay so that it is less likely to influence the remote fitting. The same hearing aids used at the in-clinic hearing aid fitting will be reset in-clinic and programmed through hearing aid software to 100% acclimatisation using NAL-NL2 prescription targets for long-term hearing aid wearers. The hearing aids will be programmed to allow for a remote hearing aid connection.
The hearing aids will be sent to the participant via courier.
At the scheduled hearing aid fitting appointment time, the clinician will telephone the participant to confirm the app installation and Bluetooth pairing was successful. The participant and clinician will then connect through the app for a remote support session.
Remote support allows an audio-video link between the participant and clinician. The clinician will connect to the participant’s hearing aids through a Bluetooth connection with the participant’s smartphone or tablet.
When both the participant and the clinician are connected to the remote support appointment, the clinician will perform proxy verification measurements through the hearing aid manufacturer software.
Hearing aid settings will be optimised using subjective participant feedback to balance overall volume, perceived sound quality, and perception of own voice/occlusion. This process will follow an interview-style approach, with the participant asked to comment on each component and the clinician making small adjustments to the hearing aid settings until the participant is happy with the sound.
The hearing aid settings will be saved, and the participant will return the hearing aids to the clinic through return-post courier.
Group Allocation
Participants will be randomly assigned to one of two groups (“Group A” and “Group B”). Group A will test the remotely-fit hearing aids first, followed by the in-clinic fit hearing aids. Group B will test the in-clinic fit hearing aids first, followed by the remotely fit hearing aids. The participants will be blind to group and order of hearing aids, as will the clinician performing follow-up appointments and assessments.
First and Second Interventions
The hearing aids will be programmed with the pre-saved settings that relate to each participant’s group allocation. Two weeks after the final fitting appointment, the participants will be sent the hearing aids via courier. They will be instructed to wear them for at least 8 hours per day for two weeks.
At the end of these two weeks, all participants will have a follow-up appointment via remote support with a clinician who is blinded to the groups. At this appointment, the participants will have the opportunity to have the hearing aids settings adjusted by the clinician in order to optimise the sound for their personal preferences. This process will follow an interview-style approach, with the participant asked to comment on overall volume, overall sound quality, performance in quiet, performance in noise, and perception of own voice. The clinician will make small adjustments to the hearing aid settings until the participant is satisfied with the sound.
Participants will be instructed to wear the hearing aids for a further two weeks, and then return to the clinic for the first outcome assessment. The hearing aids will be returned to the clinic at this time.
The second intervention will follow the same process as the first, with the hearing aids programmed with the alternate settings.
Criteria for discontinuing or modifying allocated interventions {11b}
Interventions will not be modified during the study. Participants will remain on the study unless they withdraw themselves.
Strategies to improve adherence to interventions {11c}
Adherence can be monitored at two-week intervals through hearing aid data-logging software that includes use-tracking data.
Relevant concomitant care permitted or prohibited during the trial {11d}
Participants will wear the provided hearing aids during the study in place of their existing hearing aids.
Provisions for post-trial care {30}
At the end of the intervention period, participants will return to their existing hearing aids under the care of their personal audiologist.
Outcomes {12}
Participants will attend an in-clinic appointment to measure outcomes.
Primary Outcome
The primary outcome is the absolute difference between the 4FREAR for each intervention.
The clinician will measure the real-ear aided response of each hearing aid following the NZAS Best Practice Guidelines using a Natus Aurical Freefit and Otometrics Otosuite PMM module for soft (55dB), medium (65dB) and loud (75dB) signal outputs using the International Speech Test Signal, and an on-ear Maximum Power Output measurement at 85dB (19).
Secondary Outcomes
Secondary outcome measures include:
- Estimated speech intelligibility measured by the Speech Intelligibility Index (SII) of each hearing aid fitting. An SII of zero indicates no intelligible speech and a score of one indicates all speech information is available to the participant. The REAR allows an SII to be calculated for each signal strength, allowing for comparison between interventions.
- Hearing-related quality of life measured using the Hearing Handicap Inventory for Adults (HHIA), a 25-item questionnaire that measures hearing-related QOL across social- and emotional- subdomains (27).
- Hearing aid benefit measured using the Abbreviated Profile of Hearing Aid Benefit (APHAB), a 24-item questionnaire that measures hearing aid benefit across four subscales: ease of communication (EC), reverberation (RV), background noise (BN), and aversiveness (AV)
- Sound quality and preference measured on 5-point Likert scales. Participants are asked to rate the overall sound quality of each intervention, and rate their preference between the interventions.
- Process acceptability (how likely the participant is to recommend the process to another person) measured as a net promotor score for each intervention.
- Speech-in-Noiseability measured for each intervention with an unaided and aided quick speech-in-noise (QSIN) test. QSIN will be performed according to the QSIN user guide in a calibrated testing room with speech and background noise (four-speaker babble) presented from a single speaker in front of the participant at a level of 65 dB HL. A QSIN score for each intervention will be calculated from the average SNR loss across 3 standard test lists.
Participant timeline {13}
Figure 2 shows the schedule of enrolment, interventions and assessments.
Sample size {14}
Sixty participants (thirty per group) will be recruited for the trial. This will provide 90% power at the 5% significance level to detect an overall clinically meaningful difference of 5dB 4FREAR and allow for up to 10% attrition.
Recruitment {15}
Recruitment will take place through the University of Auckland Hearing and Tinnitus Clinic and through private audiology clinics in the Auckland region. Recruitment will be via flyers and posters in clinic and on social media (Facebook and Instagram) networks. Posters will also be disseminated through audiologist networks so that they can invite people to participate in the study.
Assignment of interventions: allocation
Sequence generation {16a}
Eligible participants will be grouped according to degree of hearing loss (slight, mild, and moderate, according to WHO classifications (1)) to ensure an even spread of hearing levels between intervention groups. Participants within each hearing loss group will be assigned a random number as per a computer-generated randomisation schedule, then allocated to group A or B in the order ABAB, with an allocation ratio of 1:1.
Concealment mechanism {16b}
Participants are assigned to one of the intervention groups but the group is concealed from them. Clinicians are not aware of which groups the participants have been assigned.
Implementation {16c}
All participants who meet the eligibility criteria and complete the in-clinic and remote hearing aid fitting process will be randomised and assigned to an intervention group by a trained clinical research assistant.
Assignment of interventions: blinding
Who will be blinded {17a}
This is a double-blind study. Both the participants and the clinicians will be blind to the allocation of groups and order of intervention. The hearing aids settings and real-ear measurements will be stored anonymously so that the clinician is unable to determine what fitting process was used. The participants and clinicians will be aware of the intervention strategy at the fitting process (in-clinic or remote), which occurs prior to group allocation and blinding.
Procedure for unblinding if necessary {17b}
There is no requirement for unblinding.
Data collection and management
Plans for assessment and collection of outcomes {18a}
Primary and secondary outcome measurements will be assessed four weeks after each intervention at an in-clinic appointment.
Plans to promote participant retention and complete follow-up {18b}
All participant appointments will be confirmed 2 weeks and 48 hours prior to each appointment. All outcome assessments will be completed in person.
Data management {19}
Data will be managed through REDCap.
Confidentiality {27}
Data will be maintained electronically on a secure and confidential server at the University of Auckland.
Plans for collection, laboratory evaluation and storage of biological specimens for genetic or molecular analysis in this trial/future use {33}
Not applicable for this study as there are no biological specimens.
Statistical methods
Statistical methods for primary and secondary outcomes {20a}
The primary outcome measure is the absolute difference between average REAR measures. Secondary measures will be modelled as a 4-way repeated measures general linear model with ear (right and left), frequency (500, 1000, 2000, 4000Hz), signal input level (55dB, 65dB, 75dB), and fitting method (in-clinic or remote). All statistical tests will be two-sided at the 5% significance level.
Interim analysis {21b}
There is no planned interim analysis.
Methods for additional analyses (e.g. subgroup analysis) {20b}
There is no planned additional analysis.
Methods in analysis to handle protocol non-adherence and any statistical methods to handle missing data {20c}
All treatment evaluations will be performed on the principle of intention-to-treat (ITT), using the observed data collected from all randomised participants.
Plans to give access to the full protocol, participant level-data and statistical code {31c}
Anonymised data will be made available to other researchers on request for future research in accordance with the University of Auckland data governance policy.
Oversight and monitoring
Composition of the coordinating centre and trial steering committee {5d}
The study team comprises the authors and a clinical research assistant. The study team will meet monthly to review processes.
Composition of the data monitoring committee, its role and reporting structure {21a}
Not applicable for this study.
Adverse event reporting and harm {22}
This is a very low risk study for participants. Participants are able to withdraw from the study at any time and return to their existing hearing aids with their primary audiology provider.
Frequency and plans for auditing trial conduct {23}
The study team will meet monthly to review all aspects of the study.
Plans for communicating important protocol amendments to relevant parties (e.g. trial participants, ethical committees) {25}
Any changes to the study protocols will require review by the New Zealand Government Health and Disability Ethics Committee.
Dissemination plans {31a}
The final study outcomes will be prepared for publication and dissemination. Participants will have access to an overview of the results.