The perception of ultrasonic signals in quiet and noise by mice exposed to noise

Abstract

High-intensity noise exposures can lead to temporary or permanent increases in hearing thresholds for simple and complex stimuli. Mice produce complex signals known as ultrasonic vocalizations in a variety of behavioral contexts and it is thought these vocalizations serve a communicative function. The effects of a 2-h exposure to 8–16 kHz narrowband noise at 100 dB SPL on auditory sensitivity thresholds for two types of ultrasonic vocalizations (complex and downsweep vocalizations) in two different listening conditions (quiet and continuous 60 dB white noise) were measured. Male and female mice ranging from 100 to 1000 days old were trained to detect the vocalizations in a go/no-go operant conditioning paradigm with positive reinforcement. Each mouse participated in only one condition. Once consistent thresholds were obtained for a mouse, they were subjected to the noise exposure. Post-noise thresholds were obtained on a daily basis for up to 120 days. Similar to humans exposed to a traumatic noise, there was a lot of variability in the extent of the hearing loss following the noise exposures, with some mice experiencing large threshold shifts and other mice exhibiting only minor, temporary hearing loss. [Work supported by NIH DC016641.]