CAREER: Towards a complete picture of communication in anthropogenic noise - Auditory processing among urban and rural soundscapes.

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Noise generated by human activity has increased dramatically over the past decades and is considered a major source of pollution. High levels of noise can have negative effects on animals, particularly those that communicate with sounds. Several studies have investigated how human-generated noise can impair the recognition of vocal communication signals. Interestingly, some studies have shown changes in signals produced by animals that live in cities that help them cope with the negative effects of noise. Whether and how the sense of hearing can change in response to human-generated noise is not known. Studying the iconic ‘ribbit’ of Pacific chorus frogs, this project explores precisely this. We will compare the calls and the hearing abilities of frogs that live in urban and rural regions across the San Francisco Bay Area. We will also study whether such changes in calls and hearing abilities allow animals to communicate easier in noisy environments. Further, we will explore whether changes in hearing among urban and rural populations are related to changes in the structure of the ear. These research activities will be complemented by educational activities, including research training of diverse student populations and science education outreach in local communities. As this project will further our understanding of the consequences of noise pollution for sensory perception and behavior, our results can inform conservation and urbanization efforts and promote progress in the design of communication devices that interact with humans. Anthropogenic noise has dramatically increased over the past decades, becoming a major form of pollution. Accordingly, there is growing interest in understanding the effects of anthropogenic noise on animal behavior. For animals that communicate acoustically, anthropogenic noise can impair the detection and recognition of vocal signals. Several studies have investigated how vocal signals and signaling behaviors change to minimize the detrimental effects of anthropogenic noise. In contrast, we do not know whether the hearing capabilities of urban animals also change to better cope with high levels of noise. The central hypothesis of this project is that, among populations with different levels of natural and anthropogenic noise, the auditory system varies in ways that facilitate signal reception. We will test this hypothesis using Pacific chorus frogs (Hyliola regilla) from populations with low and high levels of natural and anthropogenic noise. Specifically, we will (i) characterize the acoustic environment (soundscape) and vocal signals of populations with different levels of noise, (ii) determine how auditory processing abilities vary among soundscapes, (iii) determine how such variation in vocalizations and hearing abilities relate to acoustically-mediated mating behavior, and (iv) examine anatomical mechanisms underlying population-level variation in auditory processing abilities. By combining behavioral, physiological, and anatomical studies of auditory processing, this project will further our understanding of how novel environments shape sensation, perception, and animal communication systems in general. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.