Abstract
Purpose:
Over-the-counter (OTC) hearing aids can potentially improve access to hearing-health care and enable individuals with mild-to-moderate hearing loss to self-manage their condition. This study compared the usability and performance of a range of self-fitting over-the-counter (OTC-SF) hearing aids.
Research Design:
This cross-sectional study evaluated six OTC-SF hearing aids.
Study Sample:
Forty-three adults with self-perceived mild-to-moderate hearing difficulties participated in this study.
Data Collection and Analysis:
Participants were randomly assigned to two of six OTC-SF hearing aids and used the manufacturer-provided instructions and smartphone applications. These hearing aids included HP Hearing PRO, Jabra Enhance Plus, Lexie B2 Powered by Bose, Lexie Lumen, Soundwave Sontro, and Sony CRE-C10. Usability was assessed based on the fitting time, hearing aid skills and knowledge (HASK), self-reported ease of the SF process, and Post-Study System Usability Questionnaire (PSSUQ) results. Performance was evaluated using the judgment of sound quality (JSQ) test and speech-in-noise benefit using the digits-in-noise and quick speech-in-noise tests.
Results:
Fitting time ranged from 14.4 to 27.1 min, with Lexie Lumen requiring the longest time (27.1 min; standard deviation [SD], 5.9 min) and HP Hearing PRO requiring the shortest time (14.4 min; SD = 1.9 min). The HASK scores varied, with Soundwave Sontro achieving the highest score (8.9/10) and HP Hearing PRO achieving the lowest score (6.8/10). Self-reported ease of SF and PSSUQ scores did not differ significantly between the OTC-SF hearing aids. Overall sound quality and clarity ratings significantly differed, with Lexie B2 receiving the highest rating (8.1/10 and 7.5/10) and HP Hearing PRO receiving the lowest rating (6.3/10 and 5.1/10). Speech-in-noise benefit did not differ significantly between devices. A thematic analysis identified seven themes of the participants’ SF experiences and six themes of the researcher’s field notes. Participants generally considered OTC-SF hearing aids user-friendly, although issues with Bluetooth connectivity, handling and insertion, and sound quality were noted by the researcher as common challenges.
Conclusions:
Usability and performance of OTC-SF hearing aids were similar across devices in terms of usability and speech-in-noise benefits. However, the devices exhibited variations in fitting time, HASK, and sound quality, including the overall impression and clarity. These findings can support the decisions of consumers and recommendations of health-care professionals. Further research of the long-term usability and selection processes of OTC-SF hearing aids is necessary.
Keywords: over-the-counter hearing aids, direct-to-consumer hearing devices, hearing aids, usability, performance
Hearing loss is a prevalent sensory impairment that affects 430 million people worldwide (World Health Organization, 2021). Although hearing aids have been the primary intervention for hearing difficulties (World Health Organization, 2021), barriers such as cost, limited access, and stigma have hindered their widespread adoption (Knudsen et al, 2010; Knoetze et al, 2023). Globally, less than 11 percent of individuals with disabling hearing loss use hearing aids (Bisgaard et al, 2022). Significant developments in hearing technology have been developed over the past decade, including advanced prescription hearing aids and direct-to-consumer devices, such as personal sound amplification products, hearables, and consumer audio devices (Manchaiah et al, 2017, 2019; Tran and Manchaiah, 2018). These innovations have paved the way for new service delivery models such as over-the-counter (OTC) hearing aids. OTC hearing aids have emerged as a promising alternative that can potentially improve access to hearing-health care and enable individuals with mild-to-moderate hearing loss to self-manage their condition (Food and Drug Administration, 2022).
On October 17, 2022, the Food and Drug Administration (FDA) established a new OTC hearing aid category that allows consumers with perceived mild-to-moderate hearing loss to purchase hearing aids directly from stores or online retailers without a medical examination, prescription, or fitting by an audiologist (Food and Drug Administration, 2022). Additionally, this new OTC hearing aid category has been divided into the following two subcategories: 1) OTC hearing aids with standardized output profiles (i.e., pre-set [PS] OTC [OTC-PS] programs) and 2) self-fitting (SF) OTC (OTC-SF) hearing aids that allow users to program and customize their hearing aids according to their needs and preferences (Food and Drug Administration, 2022).
The concept of SF hearing aids was introduced more than a decade ago (Convery, Keidser, Dillon et al, 2011). Convery et al (2017) evaluated the SF process of a commercially available hearing aid and found that most participants could complete this process without error; however, they noted that the success rate could be improved by support from trained personnel and through improvements of the design and instructions. Keidser and Convery (2018) further emphasized that with the appropriate design and support, SF hearing aids can become a more affordable and accessible option.
Recent studies of OTC-SF hearing aids related to the newly established FDA category have demonstrated benefits and satisfaction comparable to audiologist-fit hearing aids for individuals with self-perceived mild-to-moderate hearing loss (Sabin et al, 2020; De Sousa et al, 2023). The World Health Organization (2021) and Knoetze et al (2023) validated an OTC-SF method using a Bose prototype hearing aid that enabled users to select their signal processing parameters using a mobile application consisting of two dials that simultaneously control the gain and compression of all frequency bands. Furthermore, Sabin et al (2020) found that the self-fit group reported better sound quality and no differences in clinical measures of speech-in-noise benefits and satisfaction. More recently, De Sousa et al (2023) conducted a randomized, controlled trial to compare the effectiveness of an OTC-SF hearing aid using in situ audiometry and an audiologist-fitted hearing aid using best practices. The SF parameters were determined using a proprietary algorithm with in situ threshold measurements (at 0.5, 1.0, 2.0, 3.0, 4.0, and 6.0 kHz) obtained using the hearing aids and an accompanying smartphone application. Their study found that the short-term benefits of and satisfaction with the OTC-SF hearing aids were comparable to those of the audiologist-fit hearing aids using best practices. In another large-scale, cross-sectional observational study, no differences in benefits and satisfaction were observed between individuals with prescription hearing aids that were fit by hearing-health-care professionals (n = 406) and individuals with OTC-SF hearing aids (n = 250), thus demonstrating that it is possible to obtain positive benefits and satisfaction with OTC-SF hearing aids among individuals with mild-to-moderate hearing loss (Swanepoel et al, 2023). However, we are not aware of any studies that examined the benefits of and satisfaction with commercially available OTC-SF hearing aids.
Despite promising outcomes reported by some early studies, concerns regarding the safety, handling, self-adjustment, service delivery models, counseling, audiological care, and potential for optimal benefits and adverse events of OTC hearing aids persist among hearing-health-care professionals (Manchaiah et al, 2023). One study (Manchaiah et al, 2023) in 2023 revealed that more than 50 percent of hearing-health-care professionals expressed opposition to OTC hearing aids because of these concerns. Additionally, consumer attitudes toward OTC hearing aids highlight apprehensions regarding the direct-to-consumer model, with 84 percent expressing uneasiness and a preference for in-person consultations with hearing-health-care professionals (Singh and Dhar, 2023). Notably, older adults and individuals with less interest in hearing aids were less inclined toward OTC options; however, those with prior experience with direct-to-consumer models and those lacking insurance coverage were more likely to pursue OTC hearing aids. Therefore, it is crucial to evaluate the usability and performance of OTC hearing aids to ensure their safety and efficacy.
The proliferation of OTC hearing aids with unique SF strategies has occurred. However, limited research of the OTC hearing aids that are currently on the market is available (Manchaiah et al, 2023). No study has compared the SF process of OTC-SF hearing aids in terms of usability and performance, thus leaving a significant gap in the current research. An understanding of the usability and performance of different OTC-SF hearing aids is essential for several reasons. First, it empowers consumers to make informed choices, thus offering them more accessible and affordable hearing solutions and potentially enhancing their quality of life. Second, it can guide health-care professionals in recommending suitable OTC options. Third, it can contribute to establishing regulations and standards in the industry, thereby ensuring the safety and efficacy of OTC-SF hearing aids. Therefore, this study compared the usability and performance of several FDA-approved OTC-SF hearing aids available to consumers and specifically aimed to examine usability, which comprises the device fitting time, hearing aid skills and knowledge (HASK), ease of the SF process, and usability of the device, and performance, which comprises the device sound quality and speech-in-noise benefit.
MATERIALS AND METHODS
Study Design
This cross-sectional study compared the usability and performance of HP Hearing PRO, Jabra Enhance Plus, Lexie B2 Powered by Bose, Lexie Lumen, Soundwave Sontro, and Sony CRE-C10 hearing aids. We selected these specific OTC hearing aids because they were the only available OTC-SF hearing aids with a cost less than $1,000 between December 2022 and February 2023 (Table 1). Ethical clearance was obtained from the University of Pretoria Humanities Research Ethics Committee (HUM021/1122).
Table 1.
Characteristics of Self-fitting Over-the-Counter Hearing Aids (n = 6)
| Hearing Aid | Style | Price Per Pair | Rechargeable Battery | Bluetooth Streaming | Ingress Protection Rating | Application Name | Fitting Strategy |
|---|---|---|---|---|---|---|---|
| HP Hearing Pro | Earbud | $499 | Yes | Yes | IP54 | HP Hearing | In situ hearing test |
| Jabra Enhance Plus | Earbud | $799 | Yes | Yes, iPhone only | IP52 | Jabra Enhance | In situ hearing test |
| Lexie B2 | Receiver in the canal | $999 | Yes | Yes, iPhone only | IP67 | Lexie | Self-adjustment |
| Lexie Lumen | Behind the ear | $799 | No | No | IP67 | Lexie | In situ hearing test |
| Soundwave Sontro | Receiver in the canal | $849 | No | No | N/A | otoTune | In situ hearing test |
| Sony CRE-C10 | Completely in the canal | $999 | No | No | IPX4 | Sony Hearing Control | In situ hearing test |
N/A = not available.
Participants
A total of 43 participants were recruited using purposive sampling. We used various social media platforms to promote study participation and invited interested individuals to complete a Google Form to check their eligibility. Participants were asked to describe their hearing ability (without a hearing aid) by selecting one of the following options: 1) my hearing is good; 2) I have little difficulty; 3) I have a lot of difficulty; or 4) I cannot hear at all. Additionally, participants were required to rate their hearing difficulties as slight, mild, moderate, or severe. To be considered for the study, participants had to report their hearing ability as having little difficulty or a lot of difficulty and rate their hearing difficulties as mild or moderate. Eligible participants included adults (older than 18 years) who self-reported mild-to-moderate hearing difficulties and no active pathologies of the outer ear and middle ear. Additionally, participants were required to have a high level of English proficiency as determined by an online test.
To minimize potential order effects, we used a Latin square method to assign 29 participants to two of the following SF devices: Jabra Enhance Plus, Lexie B2 Powered by Bose, Lexie Lumen, Soundwave Sontro, or Sony CRE-C10 hearing aids. An additional 14 participants were recruited and assigned to self-fit the HP Hearing PRO and Lexie Lumen or Sony CRE-C10 devices. Therefore, the usability and performance of each of the six OTC-SF hearing aids were tested by 13 to 15 users. Five of 43 participants reported previous hearing aid use.
Data Collection
Self-reported and clinical measures were used to examine the usability and performance of the hearing aids. Usability included the following: device fitting time as observed and recorded by the researcher; HASK determined using the validated HASK test (Saunders et al, 2018); ease of the SF process measured using a single-item structured question and qualitative data obtained using an open-ended request for information regarding the overall SF experience and researcher field notes; and usability of the device measured using the validated Post-Study System Usability Questionnaire (PSSUQ) (Lewis, 2002). Performance included the following: device sound quality and clarity measured using the validated judgment of sound quality (JSQ) (Gabrielsson et al, 1988) self-reported rating scale and speech-in-noise benefit using the validated digits-in-noise (DIN) and quick speech-in-noise (QuickSIN) tests. Real ear measurement data were obtained but are not presented in this article.
Baseline Assessments and Fitting
Before SF the OTC-SF hearing aids, a baseline hearing assessment was conducted by a qualified audiologist. This assessment included otoscopic examination, tympanometry, pure tone audiometry, and unaided speech-in-noise tests, such as the DIN and QuickSIN, in a sound-proof booth. Additionally, participants were required to complete an online English proficiency test to ensure a high level of proficiency (https://www.efset.org). Participants self-fit their assigned OTC-SF hearing aids using an iPhone X and the manufacturer-provided instructions and accompanying smartphone application. If participants were unable to perform SF, then they could request assistance from the researcher or an accompanying family member.
Device Fitting Time
During the SF process, the researcher observed and recorded the time required for each fitting. Time was measured using a stopwatch to ensure consistency and accuracy. The timer was started when the participant opened the smartphone application, and the measurement was continuous throughout the fitting process, including periods of participant inquiry and researcher assistance. This approach aimed to capture the entirety of the fitting experience from the initial setup to final adjustments, thus offering a comprehensive understanding of the SF process.
Hearing Aid Skills and Knowledge
The researcher assessed the participants’ HASK using selected items from the HASK test (Saunders et al, 2018) immediately after SF. Importantly, participants were not expected to have prior knowledge of hearing aids upon entering the study. Instead, the HASK test was performed to assess the participants’ ability to perform essential tasks related to OTC-SF hearing aids, which was explained by the SF application instructions. These items included distinguishing left from right, inserting the right hearing aid, inserting the left hearing aid, changing the volume, and switching the hearing aids from on to off and vice versa. The items related to the batteries (because some of the OTC-SF hearing aids were rechargeable), cleaning (because the devices were clean when taken out of the box), telephone use, program use, troubleshooting, and storage were excluded because they were not relevant to all the OTC-SF hearing aids. Each item was given a score using a scale of 0 to 2 points. Participants who did not know the information or could not complete the task received 0 points. Those who were aware of the information but required assistance from the researcher received 1 point. Participants who demonstrated knowledge and performed the task correctly received 2 points. The total possible score ranged from 0 to 10.
Ease of the Self-fitting Process
After each SF process, participants were asked, “How easy was the SF process?”; then, they rated the ease using a 5-point Likert scale, with 1 indicating very easy and 5 indicating very difficult. Additionally, they were asked to respond to the following open-ended request: “Tell us about your overall experience.” The researcher recorded field notes during each fitting.
Usability of the Device:
Participants completed version 3 of the PSSUQ to measure the usability of the OTC-SF hearing aids (Lewis, 2002). The PSSUQ comprised 16 standardized questions and a 7-point Likert scale with a “not applicable” option. The overall result was determined by averaging the scores across the 7-point scale. The possible scores ranged from 1 to 7, with lower scores indicating higher usability. The PSSUQ consisted of the following three subscales: system usefulness (SYSUSE), with possible scores ranging between 1 and 7; information quality (INFOQUAL), with possible scores ranging between 1 and 7; and interface quality (INTERQUAL), with possible scores ranging between 1 and 7.
Device Sound Quality
To assess the sound quality of the OTC-SF hearing aids, we used specific items from the JSQ rating scale (Gabrielsson et al, 1988). Because of the potential challenges associated with evaluating certain items, such as fullness and spaciousness, especially immediately after fitting the OTC-SF hearing aids, we focused on rating easily understandable and reliable items. These items included the overall impression (very bad to very good) and clarity of sound (very unclear to very clear). Participants rated sound quality using a scale of 0 to 10 (11-point Likert scale), with higher scores indicating better sound quality.
Speech-in-Noise Benefit
Aided speech-in-noise tests (DIN and QuickSIN) were conducted after each fitting in a sound-proof booth at 70 dB hearing loss. The speech-in-noise benefit was assessed by subtracting the aided scores from the unaided scores.
Data Analysis
We used IBM SPSS version 28.0.1.0 to analyze the data. A preliminary analysis showed that the data violated the assumption of normality (p < 0.05) for all variables according to Shapiro-Wilk’s test. We conducted descriptive statistics to provide a comprehensive overview of the data, which included calculating measures such as the mean, median, standard deviation (SD), and range. To evaluate possible differences among the various OTC-SF hearing aids in terms of usability and performance measures, we used the Kruskal-Wallis test. Afterward, we conducted pairwise comparisons using Dunn’s (1964) procedure because it corrects for multiple comparisons. Additionally, we examined the qualitative feedback obtained from responses to the open-ended request and researcher field notes to gain insights regarding the participants’ experiences and opinions. After recognizing the need for a deeper understanding beyond quantitative measures, we performed an inductive thematic analysis to derive themes and patterns directly from the data without applying preexisting theoretical frameworks or assumptions (Braun and Clarke, 2006). The primary researcher coded the data into meaningful units of information that were then grouped into similar themes (Braun and Clarke, 2006). To include additional perspectives, we cross-checked the coding; any inconsistencies were resolved through a discussion until an agreement was reached.
RESULTS
Of the participants, 55.8 percent were male and 44.2 percent were female (Table 2). The mean age was 59.7 years (SD = 14.3 years). Regarding self-perceived hearing difficulty, 44.2 percent reported having little trouble and 55.8 percent reported having a lot of trouble. The self-perceived degree of hearing loss was reported as mild by 23.3 percent of participants and as moderate by 76.7 percent of participants. The mean pure tone averages for frequencies 0.5, 1, 2, and 4 kHz were 36.5 (SD = 16.5) for the left ear and 32.8 (SD = 16.7) for the right ear (Supplementary Figure 1).
Table 2.
Demographic Characteristics of Participants
| All Participants (n = 43) | HP Hearing PRO (n = 14) | Jabra Enhance Plus (n = 15) | Lexie B2 (n = 15) | Lexie Lumen (n = 14) | Sontro (n = 14) | Sony CRE-C10 (n = 13) | |
|---|---|---|---|---|---|---|---|
| Sex, n (%) | |||||||
| Male | 24 (55.8) | 6 (42.9) | 9 (60) | 8 (53.3) | 7 (50) | 11 (78.6) | 6 (46.2) |
| Female | 19 (44.2) | 8 (57.1) | 6 (40) | 7 (46.7) | 7 (50) | 3 (21.4) | 7 (53.8) |
| Mean age, years (SD) | 59.7 (14.3) | 60.5 (12.1) | 62.6 (13.1) | 60.9 (16.3) | 55.9 (15.2) | 60.4 (14.1) | 56.5 (16.1) |
| Self-perceived hearing difficulty, n (%) | |||||||
| I have little trouble | 19 (44.2) | 4 (28.6) | 7 (46.7) | 7 (46.7) | 4 (28.6) | 8 (57.1) | 7 (53.8) |
| I have a lot of trouble | 24 (55.8) | 10 (71.4) | 8 (53.3) | 8 (53.3) | 10 (71.4) | 6 (42.9) | 6 (46.2) |
| Self-perceived degree of hearing loss, n (%) | |||||||
| Mild | 10 (23.3) | 4 (28.6) | 2 (13.3) | 3 (20) | 2 (14.3) | 4 (28.6) | 4 (30.8) |
| Moderate | 33 (76.7) | 10 (71.4) | 13 (86.7) | 12 (80) | 12 (85.7) | 10 (71.4) | 9 (69.2) |
| Mean PTA for 0.5, 1, 2, and 4 kHz (SD) | |||||||
| Left | 36.5 (16.5) | 35.1 (18.2) | 35.0 (17.7) | 39.4 (15.9) | 35.6 (15.7) | 37.5 (15.8) | 33.7 (15.9) |
| Right | 32.8 (16.7) | 34.2 (19.1) | 35.7 (14.0) | 36.1 (16.7) | 31.4 (19.4) | 28.6 (13.9) | 28.1 (15.6) |
PTA = pure tone average; SD = standard deviation.
A summary of usability and performance measures of OTC-SF hearing aids is presented in Table 3. The device fitting time, HASK, and device sound quality (clarity and overall ratings) differed significantly between OTC-SF hearing aids (Supplementary Table 1 shows pairwise comparisons). The self-reported ease of SF, PSSUQ scores, and speech-in-noise benefit were not significantly different between OTC-SF hearing aids.
Table 3.
Summary of Usability and Performance Measures of Six Over-the-Counter Hearing Aids
| Hearing Aid (Participants) | Usability | JSQ Clarity Score,* Mean (SD) | Performance | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Device Fitting Time, Mean (SD) Min* | Self-reported Ease of Self-fitting, Mean (SD) | Overall PSSUQ Score, Mean (SD) | PSSUQ SYSUSE Score, Mean (SD) | PSSUQ INFOQUAL Score, Mean (SD) | PSSUQ INTERQUAL Score, Mean (SD) | HASK Total Score,* Mean (SD) | JSQ Overall Impression,* Mean (SD) | QuickSIN Benefit, Mean (SD) | DIN Benefit, Mean (SD) | ||
| HP Hearing PRO (n = 14) | 14.4 (1.9) | 2.1 (0.7) | 2.0 (1.3) | 2.1 (1.3) | 1.8 (1.1) | 2.2 (1.8) | 6.8 (1.3) | 5.1 (2.1) | 6.3 (1.7) | 1.2 (2.4) | −0.2 (1.7) |
| Jabra Enhance Plus (n = 15) | 19.7 (6.1) | 1.7 (0.6) | 1.8 (0.7) | 1.6 (0.7) | 1.7 (0.7) | 2.1 (1.3) | 7.3 (1.8) | 6.9 (2.1) | 6.8 (1.9) | 1.0 (2.5) | 0.4 (1.8) |
| Lexie B2 (n = 15) | 21.9 (11.4) | 2.1 (1.0) | 1.8 (0.7) | 1.8 (0.9) | 1.8 (0.7) | 1.7 (0.8) | 8.8 (1.5) | 7.5 (1.8) | 8.1 (1.2) | 1.1 (3.6) | 2.4 (4.7) |
| Lexie Lumen (n = 14) | 27.1 (5.9) | 1.7 (0.7) | 1.5 (0.7) | 1.6 (1.0) | 1.5 (0.5) | 1.4 (0.7) | 7.2 (2.0) | 6.8 (1.7) | 7.6 (1.8) | −0.8 (3.2) | −0.0 (1.8) |
| Soundwave Sontro (n = 14) | 15. 7 (5.2) | 1.8 (0.4) | 1.9 (0.9) | 1.8 (0.8) | 2.0 (1.1) | 1.8 (0.9) | 8.9 (1.4) | 6.4 (1.8) | 6.5 (1.8) | 0.00 (2.2) | −0.2 (2.2) |
| Sony CRE-C10 (n = 13) | 24.2 (6.6) | 2.4 (1.0) | 1.8 (1.0) | 1.7 (0.8) | 1.9 (1.2) | 1.8 (1.0) | 8.1 (1.9) | 6.2 (1.7) | 7.0 (1.5) | −0.5 (1.4) | 0.3 (1.2) |
| All devices (n = 85) | 20.5 (8.0) | 2.0 (0.8) | 1.8 (0.9) | 1.8 (0.9) | 1.8 (0.9) | 1.8 (1.1) | 7.8 (1.8) | 6.5 (2.0) | 7.1 (1.7) | 0.4 (2.7) | 0.5 (2.7) |
Significant difference between hearing aids according to the Kruskal-Wallis test (p < 0.05).
DIN = digits-in-noise; HASK = hearing aid skills and knowledge (scores ranging from 0 to 10, with higher scores indicating better skills and knowledge); INFOQUAL = information quality; INTERQUAL = interface quality; JSQ = judgment of sound quality (scores ranging from 0 to 10, with higher scores indicating better sound quality); PSSUQ = Post-Study System Usability Questionnaire (scores ranging from 1 to 7, with lower scores indicating better usability); QuickSIN = quick speech-in-noise; SD = standard deviation; SYSUSE = system usefulness.
Usability
Device Fitting Time
The average device fitting time ranged from 14.4 to 27.1 min across all devices (mean = 20.5 min; median = 17.0 min). Lexie Lumen had the longest average fitting time (27.1 min; SD = 5.9 min), followed by Sony CRE-C10 (24.2 min; SD = 6.6 min). HP Hearing PRO had the shortest average fitting time (14.4 min; SD = 1.9 min), followed by Soundwave Sontro (mean: 15.7 min; SD = 5.2 min). Device fitting times differed significantly (Kruskal-Wallis; χ2 (5) = 33.755 min; p < 0.001) between OTC-SF hearing aids. A post hoc analysis revealed that Lexie Lumen exhibited a significantly longer fitting time compared to that of all other OTC-SF hearing aids, except for Sony CRE-C10 (Figure 1). Furthermore, we observed significant differences in device fitting times of HP Hearing PRO and all other OTC-SF hearing aids, except Soundwave Sontro, with HP Hearing PRO requiring a significantly shorter fitting time (Figure 1).
Figure 1.
Device self-fitting duration. Boxplots include outliers, minimum (min), quartile 1 (Q1), median, quartile 3 (Q3), and maximum (max). Dashed lines represent pairwise comparisons that were significantly different (p < 0.05).
Hearing Aid Skills and Knowledge
The average HASK scores ranged from 6.8 to 8.9 out of 10 (mean = 7.8/10; median = 8.0/10). Soundwave Sontro (8.9; SD = 1.4) and Lexie B2 (8.8; SD = 1.5) had the highest average scores, whereas HP Hearing PRO (6.8; SD = 1.3) had the lowest average score (Figure 2). HASK scores (Kruskal-Wallis; χ2 (5) = 17.700; p = 0.003) were significantly different between hearing aids. Soundwave Sontro and Lexie B2 had significantly better scores than those of HP Hearing PRO, Lexie Lumen, and Jabra Enhance Plus (Figure 2). The five participants with previous hearing aid use had an average HASK score (8.2; SD = 2.2) that was similar (7.8; SD = 1.8) to that of the 38 participants who were new hearing aid users.
Figure 2.
Hearing aid skills and knowledge (HASK) scores. Boxplots include outliers, minimum (min), quartile 1 (Q1), median, quartile 3 (Q3), and maximum (max). Dashed lines represent pairwise comparisons that were significantly different (p < 0.05).
Ease of Self-fitting Rating
The average self-reported ease of SF scores ranged from 1.7 to 2.4 out of 5 (mean = 2.0; median = 2.0). Lexie Lumen had the best average self-reported ease of SF score (1.7; SD = 0.7). No significant difference between self-reported ease of SF across devices was observed. Additionally, the five participants with previous hearing aid use had an average self-reported ease of SF score (2.1; SD = 0.9) that was similar (2.0; SD = 0.8) to that of the 38 participants who were new hearing aid users.
Thematic Analysis of the Overall Self-fitting Experience
Regarding the open-ended request, the thematic analysis identified the following seven themes: ease of use and fit; physical comfort and feel; application functionality; instruction clarity; improved hearing; sound quality and noise-related problems; and user satisfaction (Table 4). Participants generally reported ease of SF for most OTC-SF hearing aids, except for Sony CRE-C10. However, we observed mixed responses regarding the physical comfort and feel of the OTC-SF hearing aids. For example, Lexie B2 users considered them comfortable to wear, whereas some HP Hearing PRO users considered them bulky and uncomfortable, and some Sony CRE-C10 users had trouble inserting them. Participants generally provided favorable feedback regarding the accompanying smartphone applications, although a few mentioned the need for improvement or review. Clear instructions were appreciated by most users, thus contributing to their overall satisfaction with the SF process. Users generally expressed satisfaction with the SF process, especially that of Lexie Lumen and Sontro Soundwave. Many users reported improved hearing and enhanced clarity as a positive outcome while using the OTC-SF hearing aids. However, some concerns about the sound quality existed, particularly with completely-in-canal or earbud-style designs such as Sony CRE-C10, Jabra Enhance Plus, and HP Hearing PRO. Users also reported issues with their own voices, echoing sounds, and feedback.
Table 4.
Thematic Analysis of Participant Responses to the Open-ended Request for Information Regarding the Overall Experience of the Self-fitting Process (n = 43)
| Theme | Example Responses |
|---|---|
| Ease of use and fit |
It is very easy. You will just have to get used to insert the hearing aids. It will take practice—ITE user
It was very easy and quick to learn—BTE user |
| Physical comfort and feel |
I find them bulky and uncomfortable—ITE user
Light on ear—BTE user |
| Application functionality |
App is easy to understand—ITE user
App needs review—BTE user |
| Instruction clarity |
Easy to follow instructions—ITE user
Very clear instructions—BTE user |
| Improved hearing |
I can hear better—ITE user
I could immediately hear better—BTE user |
| Sound quality and noise-related problems |
Sound is hollow—ITE user
Sounds clear and crisp—BTE user |
| User satisfaction |
Wow, fantastic fit and sound—ITE user
World-changing experience—BTE user |
ITE refers to earbud-style or completely-in-the-canal hearing aids and BTE refers to behind-the-ear or receiver-in-the-canal hearing aids.
App = application.
Thematic Analysis of the Researcher’s Field Notes
The researcher’s field notes revealed the following six themes: assistance with device handling and insertion; difficulties with smartphone usage; connectivity issues; technical errors and retesting; family involvement; and user experience and feedback (Table 5). During the SF process, many of the participants (n = 14) struggled with inserting and handling the devices, particularly Lexie Lumen and HP Hearing PRO hearing aids. Some participants required assistance with inserting HP Hearing PRO earbuds, changing Lexie Lumen slim tubes, or inserting Sony CRE-C10 batteries. Difficulties ranging from uneasiness using smartphones to specific issues with certain devices were noted. Connectivity problems with Bluetooth were also evident, with many participants (n = 18) struggling to pair or connect their OTC-SF hearing aids and often requiring assistance. Technical errors, such as offline servers or application malfunctions, were documented, leading to the need for retesting or obstacles during the testing phase.
Table 5.
Thematic Analysis of Field Notes Taken by the Researcher During the Self-fitting Process
| Theme | Example Notes |
|---|---|
| Assistance with device handling and insertion |
Required assistance with insertion as earbuds kept falling out—ITE user
Required assistance with inserting batteries—BTE user |
| Difficulties with smartphone usage |
Participant owns Nokia and struggled using iPhone—BTE user
Participant is not so comfortable with technology.—ITE user |
| Bluetooth connectivity issues |
Required assistance with pairing and clicked “my earbuds are not flashing blue”—ITE user
Required assistance with connectivity and prompt to click on circles—BTE user |
| Technical errors and retesting |
Cloud server offline—ITE user
App only recorded in situ test results for one ear or no results were recorded —BTE user |
| Family involvement |
Daughter assisted a lot—ITE user
Husband assisted—BTE user |
| User experience and feedback |
Participant mentioned that his own voice echoes—ITE user
Participant mentioned that the app’s text could be bigger (not the first to mention)—BTE user |
ITE refers to earbud-style or completely-in-the-canal hearing aids and BTE refers to behind-the-ear or receiver-in-the-canal hearing aids.
App = application.
Furthermore, family members played an active role in assisting some participants throughout the SF process. Participants provided diverse feedback regarding their experiences, with some expressing concerns about sound quality or application functionality. For instance, some participants reported hearing their own voice while wearing Jabra Enhance Plus hearing aids, and a few were unsure when Lexie B2 hearing aids were switched on because they had not yet placed them in their ears to hear the activation tune when connecting the devices to the smartphone. One participant was unable to complete SF of the Sony CRE-C10 because the application indicated that the participant’s hearing loss was too severe for hearing aid use according to the in situ hearing test results.
Usability
Lower PSSUQ scores indicated better usability. The average overall PSSUQ score ranged from 1.5 to 2.0 (mean = 1.8; median = 1.5). Lexie Lumen had the best average overall PSSUQ score and best overall subscale scores (Table 3). HP Hearing PRO had the worst average overall PSSUQ score (2.0; SD = 1.3), PSSUQ SYSUSE score (2.1; SD = 1.3), and PSSUQ INTERQUAL score (2.2; SD = 1.8). However, there was no significant difference between these measures of the OTC-SF hearing aids.
Performance
Device Sound Quality
Average overall impression ratings ranged from 6.5 to 8.1 out of 10 (mean score = 7.1; median score = 7.0). Lexie B2 (8.1; SD = 1.2) and Lexie Lumen had the highest average overall impression ratings (7.6; SD = 1.8), whereas HP Hearing PRO (6.3; SD = 1.7) and Soundwave Sontro (6.5; SD = 1.8) had the lowest average overall impression ratings (Figure 3). Overall impression ratings (Kruskal-Wallis; χ2 (5) = 11.168; p = 0.048) were significantly different between OTC-SF hearing aids, with HP Hearing PRO having a significantly lower rating than that of Lexie Lumen and Lexie B2. The rating of Soundwave Sontro was also significantly lower than that of Lexie B2 (Figure 3).
Figure 3.
Judgment of sound quality (JSQ) overall impression scores. Boxplots include outliers, minimum (min), quartile 1 (Q1), median, quartile 3 (Q3), and maximum (max). Dashed lines represent pairwise comparisons that were significantly different (p < 0.05).
The average clarity ratings ranged from 5.1 to 7.5 (mean = 6.5; median = 7.0). Lexie B2 had the highest average clarity rating out of 10 (7.5; SD = 1.8), whereas HP Hearing PRO had the lowest clarity rating out of 10 (5.1; SD = 2.1). Clarity ratings (Kruskal-Wallis; χ2 (5) = 12.988; p = 0.023) significantly differed between OTC-SF hearing aids, with HP Hearing PRO having a significantly lower rating than that of Lexie B2, Lexie Lumen, and Jabra Enhance Plus. The rating of Lexie B2 was also significantly higher than that of Sony CRE-C10 (Figure 4).
Figure 4.
Judgment of sound quality (JSQ) clarity scores. Boxplots include outliers, minimum (min), quartile 1 (Q1), median, quartile 3 (Q3), and maximum (max). Dashed lines represent pairwise comparisons that were significantly different (p < 0.05).
Speech-in-Noise Benefit
The average speech-in-noise benefit of the QuickSIN ranged from −0.8 to 1.1 (mean = 0.4; median = 0). The average speech-in-noise benefit for the DIN ranged from −0.2 to 2.4 (mean = 0.5; median = 0.2). The speech-in-noise benefit was not significantly different between OTC-SF hearing aids.
DISCUSSION
The usability and performance across the six FDA-approved OTC-SF hearing aids demonstrated similar general trends of usability (PSSUQ scores) and speech-in-noise benefit (QuickSIN). However, differences in certain measures, such as fitting time, HASK, and sound quality, including overall impression and clarity, were evident.
Overall, the usability scores of the PSSUQ were similar across devices and better than the means provided by 21 different studies (Sauro and Lewis, 2016), suggesting that OTC-SF hearing aids were generally user-friendly. Lexie Lumen consistently demonstrated higher overall PSSUQ scores and higher scores of all the subscales, potentially because of clear application-based instructions and demonstrational videos that supported usability, similar to previous findings (Convery et al, 2019). Device fitting time, however, varied among different OTC-SF hearing aids, and Lexie Lumen required the longest initial setup time. This may have been partly attributable to some users who struggled to measure and select the correct slim tube size before learning how to insert them. These differences in fitting time may have implications for user satisfaction and convenience; however, these implications were not observed during the current study. Users who prioritize a comprehensive introduction to OTC-SF hearing aids and precise adjustments may prefer devices such as Lexie Lumen. Additionally, those who value a faster fitting process may opt for other OTC-SF hearing aids with shorter-duration fittings. Ultimately, the user’s preference should be considered with other usability and performance measures.
This study also highlighted differences in HASK across different devices that are potentially linked to the effectiveness of user instructions provided by the applications associated with these OTC-SF hearing aids. Most users appreciated the clear instructions provided by the accompanying smartphone applications, as evidenced by the thematic analysis. Incorporating strategies such as using larger fonts, pictogram illustrations, or videos and using everyday language may aid users when performing SF and managing their hearing aids (Convery, Keidser, Hartley, et al, 2011). The application design and access to clear and comprehensive user instructions can significantly impact the user’s abilities to self-fit and manage the hearing aids, which are important to the successful achievement of benefits and satisfaction (Saunders et al, 2017). Better hearing aid handling can increase hearing aid use and improve user satisfaction (Mothemela et al, 2024). The overall quality and suitability of hearing health information are important to improving the adoption and use of as well as the benefits and satisfaction associated with hearing devices (Manchaiah et al, 2020).
According to the responses to the open-ended request, participants generally reported ease of SF for most OTC-SF hearing aids, except for Sony CRE-C10. The researcher documented several challenges faced by the participants when SF Sony CRE-C10 hearing aids. First, some participants had trouble inserting the batteries and distinguishing between the left and right markers because they were very small. Second, many participants attempted to close both battery doors simultaneously before connecting the hearing aids, which caused connection failures because the devices could connect only one at a time. Third, one participant could not complete the SF process for Sony CRE-C10 hearing aids because its control application indicated that the participant’s hearing loss was too severe for the hearing aids to be effective based on the in situ hearing test results. Finally, as with the other in-the-ear devices (i.e., Sony CRE-C10, Jabra Enhance Plus, HP Hearing PRO), participants raised concerns about hearing their own voice, echoing sounds, and feedback. This information underscores the importance of form factors, device designs, and user interfaces, which can significantly impact the overall user experience. Individuals who prefer more situational use may prefer this form factor, whereas those who prefer to use their devices all day may prefer behind-the-ear styles; however, further studies of these preferences should be performed.
Similar to the findings of another study (Convery et al, 2019), some participants were not able to perform SF independently and required assistance from the researcher or family members during the process. The need for assistance with Bluetooth connectivity for most OTC-SF hearing aids suggested that improvements may be necessary in terms of user-friendly Bluetooth pairing and connectivity. Therefore, despite the generally user-friendly nature of OTC-SF hearing aids, some individuals may require assistance during the SF process. OTC hearing aid users should recognize the potential need for assistance and, perhaps, involve their significant other in the SF process. Audiological rehabilitation models recommend the involvement of significant others in the rehabilitation process to significantly improve benefits and satisfaction (Manchaiah et al, 2012; Hickson et al, 2014). Moreover, hearing-health-care professionals can also offer valuable support services to some individuals who use OTC-SF hearing aids and require additional support, thus ensuring a smoother SF process and user experience.
In terms of performance, behavioral outcomes such as speech-in-noise benefit were similar across devices. Device sound quality ratings, however, varied significantly among different OTC-SF hearing aids, suggesting that some may provide a more satisfactory listening experience in terms of overall sound quality and clarity. For users, these factors may influence their perception of the effectiveness of the OTC-SF hearing aids and overall satisfaction (Mothemela et al, 2024). In line with the findings of Manchaiah et al (2019), we found that higher-priced devices, such as Lexie B2 and Sony CRE-C10, may provide better sound quality compared to that of lower-priced devices, such as HP Hearing PRO (Table 1). However, such benefits were not replicated in behavioral measures of speech-in-noise. Users may consider sound quality as an important factor when selecting OTC-SF hearing aids, whereas hearing-health-care providers can use this information to guide users toward options that align with their expectations and preferences. These results suggest the need for consumer-centric metrics of audio performance that can aid consumers in decision-making when evaluating OTC hearing aids for purchase.
Study Limitations and Future Directions
This is the first study to use a structured method to examine the usability and performance of OTC-SF devices that are currently on the market and provide timely knowledge. However, this study had a few limitations. Only six OTC-SF hearing aids were evaluated. Therefore, the entire spectrum of available OTC-SF devices that are rapidly entering the market was not evaluated. Moreover, very little is known about OTC-PS devices, thus potentially limiting the broader generalizability of our results. We recruited 43 participants with self-perceived mild-to-moderate hearing difficulties and good English proficiency. This specific demographic might not represent the entire population who could benefit from OTC-SF hearing aids. This study was conducted in a controlled environment in which users were observed, thus potentially influencing their behavior and responses. Participants may have been more attentive or felt pressured to perform better than they would in their typical daily settings. Additionally, this controlled environment did not fully replicate real-world conditions in which various distractions and environmental factors could impact the usability and performance of OTC-SF hearing aids. Speech-in-noise tests were not counterbalanced between aided and unaided conditions. The selective inclusion of HASK items offered a focused evaluation aligned with the study objectives but may have compromised the construct validity and potentially introduced bias, which should be considered when interpreting the scale results. However, comparisons within subjects and between devices were performed, thus mitigating potential bias effects.
Longitudinal studies should evaluate the performance and usability of OTC-SF hearing aids over extended periods to provide valuable insights regarding long-term effectiveness and user satisfaction. Furthermore, an investigation of the decision-making process when selecting OTC-SF devices would offer useful information about user preferences and factors that influence user choices. An investigation of whether previous hearing aid use affected the usability and performance of OTC devices could provide essential insights regarding potential differences in user experience.
Investigating the level of assistance needed during SF and its potential impact on user experience could provide valuable insights for family members or health-care professionals, thus helping them to support OTC-SF users and optimize their hearing aid experience. Incorporating assessments of vision and dexterity could enhance our understanding of how these factors influence the usability and performance of OTC devices, thereby contributing to more comprehensive user-centric evaluations. Moreover, exploring the usability, performance, and benefits of and satisfaction with OTC-PS hearing aids can help improve our understanding of the benefits and limitations of OTC-PS hearing aids. Finally, researchers should compare the benefits and satisfaction associated with different OTC-SF hearing aids to determine their effectiveness.
CONCLUSION
This study demonstrated similar usability and performance across multiple OTC-SF hearing aids, except for a few dimensions, including device fitting time, HASK, and sound quality. These differences may be important to users because they provide valuable insights regarding the tradeoffs associated with different devices. Qualitative feedback from participants who used the in-the-ear designs emphasized the need for further refinement of acoustics and fitting techniques to mitigate challenges related to self-perception of sound. Furthermore, improvements in user-friendly Bluetooth pairing and connectivity may be necessary. The design and user interface of OTC-SF hearing aids play important roles in the user experience. Further improvements in these areas, such as clear and comprehensive instructions, may enhance overall usability and satisfaction. These findings can support consumers and hearing-health-care professionals when making informed decisions and recommendations regarding OTC-SF hearing aids. Further studies should explore the device selection process, long-term usability, and satisfaction with OTC-SF and OTC-PS hearing aids.
Abbrevations:
- DIN
digits-in-noise
- FDA
Food and Drug Administration
- HASK
hearing aid skills and knowledge
- INFOQUAL
information quality
- INTERQUAL
interface quality
- JSQ
judgment of sound quality
- OTC
over-the-counter
- OTC-SF
self-fitting over-the-counter
- OTC-PS
pre-set over-the-counter
- PS
pre-set
- PSSUQ
Post-Study System Usability Questionnaire
- QuickSIN
quick speech-in-noise
- SD
standard deviation
- SF
self-fitting
- SYSUSE
system usefulness
Footnotes
Any mention of a product, service, or procedure in the Journal of the American Academy of Audiology does not constitute an endorsement of the product, service, or procedure by the American Academy of Audiology.
Supporting information
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