Physiological and perceptual auditory consequences of hunting-related recreational firearm noise exposure in young adults with normal hearing sensitivity

Abstract

Purpose: The objective of the current study was to describe outcomes on physiological and perceptual measures of auditory function in human listeners with and without a history of recreational firearm noise exposure related to hunting.

Design: This study assessed the effects of hunting-related recreational firearm noise exposure on audiometric thresholds, oto-acoustic emissions (OAEs), brainstem neural representation of fundamental frequency (F0) in frequency following responses (FFRs), tonal middle-ear muscle reflex (MEMR) thresholds, and behavioral tests of auditory processing in 20 young adults with normal hearing sensitivity.

Results: Performance on both physiological (FFR, MEMR) and perceptual (behavioral auditory processing tests) measures of auditory function were largely similar across participants, regardless of hunting-related recreational noise exposure. On both behavioral and neural measures including different listening conditions, performance degraded as difficulty of listening condition increased for both nonhunter and hunter participants. A right-ear advantage was observed in tests of dichotic listening for both nonhunter and hunter participants.

Conclusion: The null results in the current study could reflect an absence of cochlear synaptopathy in the participating cohort, variability related to participant characteristics and/or test protocols, or an insensitivity of the selected physiological and behavioral auditory measures to noise-induced synaptopathy.

Keywords: Cochlear synaptopathy; auditory processing; frequency following response; middle-ear muscle reflex; recreational firearm noise exposure.

Figure 1

Mean air conduction pure-tone thresholds for nonhunter (filled circles) and hunter (open circles) participants at audiometric test frequencies between .25 and 8 kHz for the right (panel A) and left (panel B) ears. Symbols represent the mean, whereas error bars represent the standard error across participants.

Figure 2

Mean DPOAE SNR (right ear: Panel A; left ear: Panel B) and TEOAE SNR (right ear: Panel C; left ear: Panel D) values for nonhunter (filled circles) and hunter (open circles) as a function of test frequency in kHz. Symbols represent the mean, whereas error bars represent the standard error across participants.

Figure 3

Grand average FFR_ENV time-waveforms (Panel A) and spectra (Panel B) measured in clean, +5, 0, and −5 dB SNR conditions in nonhunter (black) and hunter (red) participants.

Figure 4

Mean F0/NF values for nonhunter (filled circles) and hunter (open circles) participants as a function of the SNR (clean, +5, 0, −5 dB). Symbols represent the mean, whereas error bars represent the standard error across participants.

Figure 5

Mean MEMR thresholds for nonhunter (filled circles) and hunter (open circles) participants at .5, 1, and 2 kHz for right ipsilateral and left contralateral (Panel A), and left ipsilateral and right contralateral (Panel B) conditions. Symbols represent the mean, whereas error bars represent the standard error across participants.