The study of hearing aid durability and microbial colonization in a coastal region in India

Abstract

Background: The global burden of hearing impairment necessitates the widespread deployment of hearing aids, which serve as the primary modality for audiological rehabilitation. However, the long-term efficacy, structural longevity, and hygienic safety of these devices are significantly challenged by extreme environmental factors. High-humidity coastal environments, characterized by atmospheric salinity and elevated temperatures, pose a unique and severe threat to the sophisticated microelectronics of these devices. Furthermore, these climatic conditions fundamentally alter the microenvironment of the external auditory canal, promoting the rapid growth of pathogenic bacterial and fungal biofilms on customized earmolds and acoustic domes. This dual threat frequently leads to device failure and recurrent auricular infections.

Methods: A comprehensive, mixed-methods observational study comprising a three-year retrospective analysis of audiology repair logs and a cross-sectional microbiological study of patient earmolds was conducted in the Department of ENT, Father Muller Medical College, Mangalore located in the monsoonal coastal region of Karnataka, India. Device failures were systematically categorized, and earmold swabs were cultured for aerobic bacteria, anaerobic bacteria, and fungal flora using established microbiological protocols.

Results: Analysis of 412 distinct hearing aid repair logs revealed a high incidence of moisture-related mechanical and electronic failures, predominantly affecting acoustic transducers. Receivers were the most frequently failed component (38.3%), followed closely by microphones (29.1%). The cross-sectional survey of 150 active earmolds demonstrated an alarming 78% microbial colonization rate. Fungal elements, particularly Aspergillus spp., and opportunistic bacteria, notably P. aeruginosa, were the most prevalent isolates, frequently presenting as polymicrobial biofilms.

Conclusions: High-humidity coastal climates significantly accelerate the degradation of hearing aid microelectronics through galvanic corrosion and moisture ingress, while simultaneously fostering opportunistic, pathogenic microbial biofilms within the ear canal. Enhanced environmental structural protections, active dehumidification technologies, and highly stringent antimicrobial hygiene protocols are absolutely essential to sustain audiological rehabilitation and safeguard otologic health in tropical regions.