Acoustic trauma inducing ‘low frequency’ sensorineural hearing loss; A cross-sectional study among medical students using Pure Tone Audiometry

Abstract

Objectives: This study aimed to ascertain current practices prevalent among medical students using electroacoustic devices. We also aimed to determine pattern and frequency of hearing loss among medical students. Design: Cross-sectional Participants: Students of 3rd year and 4th year MBBS at Jinnah Sindh Medical University, Karachi, Pakistan were included. Data collection dated from December 2019 till February 2020 using convenience sampling technique. Setting: Students were invited to ENT OPD, Jinnah Postgraduate Medical Centre, Karachi. Through a structured proforma, we recorded practices regarding electroacoustic devices. We investigated hearing of medical students by tuning fork tests and Pure Tone Audiometry. Main Outcome Measures: Using SPSS software version 23 we applied Chi square test, Pearson correlation and independent t test at 95% CI and p=<0.05 as significance level. Results: A total of 221 students fulfilled inclusion criteria. 96.4%(n=213) regularly used electroacoustic devices. Students mostly used insert type earphones connected with a smartphone. More than 30% of medical students demonstrated low frequency (0.25-0.5kHz) sensorineural hearing loss (SNHL). Pearson correlation yielded strong positive correlation with hearing loss and years of exposure(p=<0.001). Male students used electroacoustic devices more frequently than female students(p=0.01). However, we did not observe significant difference between their mean thresholds. Conclusion: Acoustic trauma has been conventionally described to affect higher frequencies. We found low frequency SNHL among majority of students. This indicates that specific type of acoustic trauma can affect particular frequencies on audiogram. KEY WORDS: Low frequency hearing loss, medical students, Pure Tone Audiometry, personal listening devices, hearing thresholds, noise induced hearing loss, sensorineural hearing loss