PP708 - Relationship Between Threshold Shift Susceptibility and External-Ear Amplification Following Video Game Exposure

Abstract: This study tested the hypothesis that real-ear-unaided-gain (REUG) and real-ear-to-coupler difference (RECD) would be positively correlated with prospective temporary threshold shift following video game noise exposure. Twenty-nine participants completed otoscopy, tympanometry, pinna size measurements, REUG, RECD, DPOAEs, and audiometric testing pre-/post 2 hours of video game noise exposure. Results showed high variability in RECD and REUG values; however, they were not correlated with threshold shift, possibly due to limited variability in post-exposure audiometric thresholds.

Summary: External-ear amplification (EEA) has shown a variability of 5-19 dB-A in pediatric, adolescent, and adult populations. EEA could potentially serve as a key predictor of an individual's susceptibility to noise-induced hearing loss, as exposure level variability between 5-19 dB-A suggests that individuals with higher EEA are theoretically at 3-4 times higher risk of developing NIHL compared to those with lower EEA.

The purpose of this prospective analysis was to test the hypothesis that inherently variable real-ear unaided gain (REUG) and real-ear-to-coupler difference (RECD) could be used as a more cost-effective and more efficient method of predicting individual NIHL susceptibility, measured by temporary audiometric threshold shift. Additionally, we tested the hypothesis that increased REUG and RECD would be correlated with decreased DPOAE amplitude post-exposure.

Twenty-nine adult participants (18-25 years) were exposed to 2 hours of video game noise exposure set at a volume of the participants' choice. Participants completed otoscopy, tympanometry, pinna measurements, two EEA measurements: (1) total real-ear unaided gain (REUG) of the open ear and (2) real-ear to coupler difference (RECD), representing unaided gain from the earcanal, pre-/post- Distortion Product Otoacoustic Emissions (DPOAEs) from 1 kHz to 10 kHz and pre-/post- auriometric measurements (1000-14,000 Hz). The relationships between REUG, RECD, and post-exposure hearing sensitivity were analyzed.

Open-ear REUG ranged 8-16 dB-SPL across participants, and occluded-ear RECD ranged 15-22 dB-SPL. While large variability was noted within the predictor variables (REUG and RECD), there was no reliable threshold shift (outcome variable) observed in participants after 2 hours of video game noise exposure, highlighting a limitation of study design. This limitation prompts new questions about a more intense temporary threshold shift noise exposure model for humans that still remains safe, in order to study individual variables that mitigate individual susceptibility to NIHL.

In conclusion, high variability in REUG and RECD was observed in this study across participants, however, these variables were not able to be used to predict temporary threshold shifts, even in the four participants with the largest amount of temporary threshold shift. A limiting factor in this study was that the video-game sound levels were not standardized across participants; they selected their own listening level, and so every participant served as their own control. If the listening levels were standardized, it might be possible to detect a relationship between REUG, RECD, and temporary threshold shift susceptibility.