Longitudinal effects of noise exposure and age on masked auditory brainstem response-derived estimates of auditory filters in laboratory mice

Abstract

The peripheral auditory system in normal-hearing individuals is highly tuned to discriminate very minor changes in frequency, but this frequency resolution may be susceptible to the effects of age and noise. Unfortunately, high-intensity noise damages the auditory periphery and leads to temporary or permanent hearing loss. Using a streamlined method to measure auditory brainstem responses (ABRs) in simultaneous spectrally notched noise, we measured masked thresholds and estimated peripheral frequency selectivity in male and female CBA/CaJ mice across the lifespan before and after noise exposure (8–16 kHz narrowband noise at 100 dBA SPL for 2 ). Mice were grouped by age at the time of noise exposure (44, 144, and 479 days old) and tracked longitudinally. We recorded ABRs to a 16 kHz tone in quiet, in the presence of a broadband masker, and in a masker with a spectral notch of varying widths (1/8th,1/4th, 1/2, 1, and 2 octaves centered around 16 kHz) before and after noise exposure for up to 6 months post-exposure. Our findings show that masking differs with age and time after noise exposure, and that young adult mice (<2 months old at noise exposure) are especially susceptible to traumatic noise.