Coping with City Noise: Assessing Environmental Noise and Hearing Abilities along an Urban-Rural Gradient
By: Carolyn Schwartz
Department: Biology
Faculty Advisor: Dr. Alejandro Vélez Meléndez
Anthropogenic noise, or noise generated by human activity, continues to increase to unprecedented levels, rendering it a hazardous form of pollution. This novel pollutant alters the acoustic environment and may negatively impact animal behavior, particularly as it pertains to animals that communicate acoustically. Many studies have examined how acoustic communication signals change to ameliorate the effects of anthropogenic noise. However, little is known about the physical properties of the noise and whether hearing abilities also change in response to anthropogenic noise. Here, we tested the hypothesis that the efficiency of the auditory system to detect signals in noise varies among populations exposed to different levels of natural and anthropogenic noise. We measured variation in (i) the acoustic environment and (ii) hearing capabilities in noise among eight populations of Pacific chorus frogs along an urban-rural gradient in the San Francisco Bay area. Analyses of the acoustic environment display higher levels of low-frequency noise in urban and coastal areas. Additionally, high hourly variation in noise levels was observed in both urban and rural areas. Between populations, results show minor differences in hearing abilities in noise. This is one of the first studies to provide a detailed characterization of this novel pollutant and its potential effects on hearing abilities. As this noise pollutant continues to expand, it is crucial to understand how sensory systems respond to enact plans for the conservation of species that may be detrimentally influenced.