Exposure to an Augmented Acoustic Environment Improves Signal-in-Noise Detection in Old CBA/CaJ Mice

Growing evidence suggests that neural plasticity can aid in the prevention or treatment of age-related hearing loss (ARHL). Many of these studies, conducted in both animal models and humans, utilized auditory training or passive listening to modulate and assess neural plasticity. Moreover, there remains a need for elucidation on the underpinnings of hearing improvement in challenging listening situations, such as comprehending speech in background noise. There is a paucity of published reports that have examined the effects of targeted augmented acoustic environments on hearing function, specifically signal-in-noise (SiN) processing. An augmented acoustic environment (AAE) is a paradigm first reported by Turner and Willott (2000) in which animals are exposed to a non-traumatic sound for a long period of time. They found that auditory function improved in a developmental hearing-impaired mouse model exposed to AAE. In this study we used modification of the acoustic startle response to determine whether a SiN AAE could improve SiN processing in mice with age-related hearing loss. 9 aged CBA/CaJ mice (20 months) were exposed for 2 months to an AAE consisting of a continuous Gaussian wideband noise to simulate real-life workplace background noise, with a 16 kHz tone burst presented at intensities of +3, +6, +9-, and +12-dB SPL above the background. Aged mice in the AAE group showed statistically significant improvement in detecting the signal in background noise as evidenced by increases in PPI following exposure 2 months post when compared to baseline. AAE animals also demonstrated significant improvements across several tonal prepulse frequencies at 10, 16, and 24 kHz, demonstrating that the ameliorative effects of the exposure are generalizable across the frequency domain. This study demonstrates the consequences of exposure to a SIN AAE in the aged auditory system and plasticity with respect to auditory perception in noisy environments