Practical Guidelines for Smartphone-Based Hearing Aid Application and Personal Sound Amplification Device Usage to Correct Hearing Loss in Korea Based on a Randomized Controlled Trial by the Patient-Centered Clinical Research Coordinating Center
Article information
Abstract
The prevalence of mild-to-moderate hearing loss is increasing due to noise exposure and an expanding elderly population. Despite the benefits of hearing aids, many individuals avoid them due to cost and incomplete awareness, opting instead for smartphone-based hearing aid applications (SHAAs) and personal sound amplification products (PSAPs). However, these devices are currently lacking official approval for medical use. The study results, together with roundtable discussions organized by the Patient-Centered Clinical Research Coordinating Center (PACEN) and recent research findings, were reviewed to develop clinical guidelines. The roundtable discussions involved seven otology experts and one lay representative and focused on defining PSAPs and establishing minimum requirements for their use by patients with hearing loss. Hearing aids were found to effectively address all types of hearing loss and improve speech recognition in noisy environments. In contrast, SHAA and PSAP are effective only under specific conditions: SHAA for mild loss and PSAP for mild-to-moderate loss. Both devices perform poorly in noisy settings and lack noise processing features. Hearing aids are recommended as the most effective and versatile option for auditory rehabilitation, whereas SHAA and PSAP should only be considered under defined conditions when hearing aids are impractical. Continued updates and cost-effectiveness evaluations will be required as technologies advance.
Introduction
Hearing loss and tinnitus are becoming increasingly common due to an aging population and a rise in noise-induced hearing loss, resulting in significant medical and social costs. As of 2018, the population with hearing loss in Korea is estimated to be around 8.09 million [1]. Hearing loss limits communication, academics, and work, increases the risk of accidents, and is associated with cognitive decline and dementia, necessitating active auditory rehabilitation [2]. The use of hearing aids can slow cognitive decline, reduce the incidence of dementia [3], promote social activities, decrease depression, and contribute to economic independence [4].
However, the usage rate of hearing aids remains low [5]. In the United States, only 20% of the population that needs hearing aids actually uses them, while in Korea, only 12.6% of patients with moderate or greater hearing loss use hearing aids. Additionally, only 0.47% of patients with mild hearing loss, who do not have moderate hearing loss but still require hearing rehabilitation, use hearing aids [6]. One reason for the very low usage rate of hearing aids among patients with hearing loss is the high cost of hearing aids [7]. To address this issue, the use of personal sound amplification products (PSAPs) is also recommended as an alternative to overcome accessibility problems caused by the high price of hearing aids [8].
With the widespread use of smartphones, apps equipped with sound amplification and hearing test functions have been developed and are actually being used [9]. These apps can be used on various mobile devices and provide sound amplification and noise control functions, increasing interest in the usefulness of mobile devices for auditory rehabilitation [10]. These apps include multi-channel amplification, compression and expansion, and noise reduction algorithms [11]. Since most can be downloaded for free, they can be an alternative for patients with hearing loss who are reluctant to use hearing aids due to economic reasons [12].
Previous studies have suggested that PSAPs significantly improve listening in quiet environments, but their effectiveness may be limited in noisy environments [13]. Additionally, smartphone hearing aid apps (SHAA) are gaining attention as a cost-effective alternative and are reported to potentially help improve speech recognition in hearing-impaired patients, but there is still a lack of systematic analysis on their effectiveness and limitations [14]. Public awareness surveys have shown that while people know that PSAPs are different from hearing aids, many are not familiar with SHAAs [15,16]. As the use of these devices increases, there is a growing need for clear guidelines on SHAA and PSAP.
This study aims to comprehensively analyze the effectiveness and limitations of SHAA and PSAPs, which are gaining attention as alternative devices to hearing aids for patients with hearing loss, and to provide clear guidelines on their use. The study was conducted with the support of Patient-Centered Clinical Research Coordinating Center (PACEN) from 2019 to July 2024 [15-22]. It was designed as a multi-center, prospective, randomized study involving five university hospitals in Korea. It utilized a crossover design to compare the subjective and objective efficacy and side effects of hearing aids with either SHHA or PSAPs, involving a total of about 370 participants. The study results, roundtable discussions conducted by PACEN, and recent research findings will be reviewed to propose clinical guidelines. Roundtable discussions were conducted by 7 otology experts and 1 layperson who represent the consumers. They discussed the definition of PSAP and suggest the minimal requirement for the PSAP for using the hearing loss patients.
Guidelines for the Use of Hearing Aids and Alternative Devices (SHAA, PSAP)
Purpose of the guidelines
This study aimed to evaluate the effectiveness and limitations of SHAA and PSAP to provide practical and safe usage guidelines for patients with hearing loss. While previous studies analyzed the characteristics and effects of individual devices separately, this study comprehensively analyzed the clinical efficacy of SHAA and PSAP to provide guidelines on device selection in hearing loss management [15,18-20]. Specifically, by comparing the practical auditory assistance functions provided by hearing aids, SHAA, and PSAP, and clarifying the usage conditions and limitations, we aim to help patients select more effective and appropriate devices. This provides a foundation for hearing-impaired patients to choose the optimal device for their hearing condition and environment, making an important contribution to proposing economical and practical auditory rehabilitation methods.
Guideline 1: Hearing aids are the first recommended method for auditory rehabilitation for all types of hearing loss
Hearing aids are proven to be effective for all types of hearing loss, including mild, moderate, moderate-severe, unilateral, and bilateral. Hearing aids reliably enhance speech perception and improve hearing in noisy environments due to their stable and dependable performance. They are effective across various auditory environments, and their safety has been confirmed for long-term use. As the first line of treatment for hearing-impaired patients, hearing aids are a crucial tool in auditory rehabilitation and help alleviate the social and psychological issues associated with hearing loss. Modern hearing aids offer various features, including noise suppression, directional microphones, and automatic environmental adjustments, providing a customized listening experience. SHAA or PSAP should be considered only when using hearing aids is challenging.
SHAA and PSAPs are not approved medical devices for hearing-impaired patients and are effective only under specific conditions. They notably perform poorly in noisy environments. SHAAs often face processing delays when connected via Bluetooth, which can be mitigated by using wired connections, the latest devices, or iOS products [19].
Guideline 2: It is advisable to undergo a hearing test and consult with a hearing care professional before choosing to use a hearing aid, SHAA, or PSAP
After a hearing test and consultation with a hearing care professional, it is crucial to evaluate the suitability of hearing aids and decide whether to use them. A tailored selection of hearing aids, considering the auditory needs and living environment of the hearing-impaired patient, is necessary.
Guideline 3: The use of SHAA and PSAP is recommended only for adults without ear diseases
This study was conducted only on healthy adults without ear diseases other than hearing loss. Thus, the subjects should be adults, excluding children, and should not have chronic ear diseases other than hearing loss. If there is a treatable ear condition, appropriate diagnosis and treatment of the disease should come first. For conditions like ear discharge or eardrum perforation, a doctor’s diagnosis and treatment are necessary.
Guideline 4: SHAA and PSAP can be considered for mild or some moderate hearing loss
SHAAs are mainly suitable for patients with mild hearing loss, providing sound amplification and hearing support functions [19]. These apps use smartphones to offer hearing assistance, which is easy to use and economical. However, their effectiveness may be limited for patients with moderate or more severe hearing loss, and there are limitations in improving speech perception. The performance of these apps heavily depends on the hardware and software of smartphones, and they require regular updates and maintenance. Additionally, the services provided vary by model and version, so users should be careful when choosing an appropriate app.
PSAPs can be helpful mainly for patients with mild and moderate hearing loss [22]. They offer greater sound amplification compared to SHAAs.
Guideline 5: The suitable types of hearing loss for hearing aid apps and personal sound amplifiers are flat-type hearing loss or mild high-frequency hearing loss
The electroacoustic analysis of hearing aid apps and personal sound amplifiers shows limited amplification of high frequencies, with the highest fitting consistency in flat and mild high-frequency hearing loss [19,21].
Guideline 6: SHAA and PSAP should be used in quiet environments rather than noisy ones
SHAAs provide sound amplification and hearing support functions, but their effectiveness is limited in noisy environments and depends on the smartphone’s hardware and software [13,19]. Han, et al. [15] also reported that hearing aid apps are mainly useful in quiet environments. PSAPs are useful for sound amplification and hearing support in quiet environments, but their effectiveness is limited in noisy environments. Due to the lack of noise processing capability, they may be challenging to use in noisy environments, and sound distortion may occur. PSAPs are generally affordable and easy to use but lack noise suppression features and are more challenging to customize than hearing aids.
Guideline 7: For individuals with mild hearing loss, PSAPs should be chosen for their ability to amplify speech frequencies specifically within the 0.5–4 kHz range
SHAA and PSAP should be able to amplify frequencies in the 0.5–4 kHz range, which is crucial for everyday communication. This frequency range plays an important role in human conversation and affects speech perception. Some devices may over-amplify low frequencies, reducing speech discrimination, or lack amplification of high frequencies important for speech recognition. This amplification range is a minimum standard, and most hearing aids amplify a wider range.
Guideline 8: The maximum output of SHAA and PSAP should not exceed 110 dB SPL
The maximum output should not exceed 110 dB SPL to prevent hearing damage from excessive sound. If the output is too high, it may cause additional damage to hearing, so appropriate output limits are necessary [23]. Some PSAPs provide excessive amplification, which may cause noise-induced hearing loss, requiring caution. In addition, it is recommended that manufacturers disclose key technical specifications, such as maximum output level, gain, frequency response range, total harmonic distortion, and equivalent input noise level.
Limitations and Future Technological Developments and Guideline Improvements
These guidelines clearly outline the factors hearing-impaired patients should consider when selecting devices and provide basic instructions to support practical and effective auditory rehabilitation.
The field of hearing loss management and auditory rehabilitation is continuously evolving, with new technologies constantly emerging [10]. Therefore, it is necessary to continuously evaluate the technological advancements and costeffectiveness of SHAA and PSAP to improve the guidelines. Updated guidelines reflecting the latest technologies can provide more effective and appropriate auditory rehabilitation solutions for hearing-impaired patients. New research and data following technological advancements will play an important role in updating and supplementing future guidelines.
This study has several limitations. First, clinical practice guidelines are typically developed based on a systematic review of the scientific evidence, supplemented by expert consensus and accompanied by a graded recommendation system. These guidelines should be updated regularly to reflect new evidence and evolving clinical practices. To date, this guideline will be revised through a more rigorous systematic review process, incorporating updated recommendations and graded levels of evidence on a regular basis. Second, SHAAs may have performance differences depending on the smartphone’s hardware and software, which may affect the accuracy of the study results. However, despite these limitations, this study comprehensively presented the effectiveness and limitations of devices by analyzing data considering various smartphone models. Third, there is a lack of data on the actual usage environment due to insufficient noise processing technology in PSAPs, and there is a lack of analysis of the long-term effects and side effects of prolonged use. Nonetheless, the study is significant in clearly defining the usage conditions of PSAPs and specifically analyzing their limitations, particularly in noisy environments. Fourth, the study was limited to university hospitals in a specific region, which may affect the generalization of the results. However, even within a limited environment, this study provided reliable data, which offers important information for evaluating the usefulness of devices in specific environments.
Future research directions should focus on continuously evaluating the technological advancements and cost-effectiveness of SHAA and PSAP. In particular, technological development to improve effectiveness in noisy environments and additional research on the long-term effects and side effects of devices are needed. Additionally, studies that include diverse regions and populations are needed to derive more generalized results and provide practical data for improving auditory rehabilitation solutions. Improving guidelines reflecting the latest technologies will contribute to providing more effective and appropriate auditory rehabilitation solutions for hearing-impaired patients. Such research is expected to provide fundamental data for the advancement of hearing loss management and auditory rehabilitation fields.
Conclusion
This study evaluated the effectiveness and limitations of SHAA and PSAP, providing practical and safe usage guidelines for hearing-impaired patients. Hearing aids have been confirmed to be effective across mild to moderate hearing loss and are reliable devices that operate stably in various auditory environments. In contrast, SHAA and PSAP are useful only under certain conditions and show limited effectiveness, especially for moderate or more severe hearing loss or in noisy environments.
Hearing aids are recommended as the first choice for hearing-impaired patients, while SHAA or PSAP may be considered when hearing aids are difficult to use. This study clarifies the appropriate usage conditions and selection criteria for each device, supporting hearing-impaired patients in selecting more effective and suitable auditory assistance devices. Future research needs to evaluate the technological advancements and cost-effectiveness of SHAA and PSAP, improve their effectiveness in noisy environments, and analyze long-term data. This study is expected to provide foundational data for the advancement of hearing loss management and auditory rehabilitation fields.
Notes
Conflicts of Interest
The authors have no financial conflicts of interest.
Author Contributions
Conceptualization: all authors. Formal analysis: Myeongsin Kang, Moo Kyun Park. Funding acquisition: Moo Kyun Park. Methodology: Moo Kyun Park. Project administration: Moo Kyun Park. Resources: Myeonsin Kang. Supervision: Moo Kyun Park. Validation: Moo Kyun Park. Visualization: Moo Kyun Park. Writing—original draft: Myeonsin Kang. Writing—review & editing: Myeonsin Kang. Approval of final manuscript: all authors.
Funding Statement
This research was supported by a grant from the Patient-Centered Clinical Research Coordinating Center funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI19C0481, HC19C0128).
Acknowledgments
None