Acoustic Rhythms and Beat Precision: Variation across Species, Development and Time

• Applicant: Dr. Lara Sophie Burchardt
• Subject Area: Sensory and Behavioural Biology ; Bioinformatics and Theoretical Biology ; Evolution, Anthropology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 528064681

Many species, including humans, communicate acoustically with sounds. While spectral characteristics of acoustic signals have been the main focus of research for decades, we are currently experiencing a revolution: more and more studies are now focusing on temporal parameters or rhythms. They address new and diverse questions that cannot be answered by studying spectral parameters alone. However, the full potential of acoustic rhythms to help answer questions about species identity, physiology, cognition, ecology, and animal behavior has yet to be realized. Another unanswered question is on the origin and adaptive function of such rhythms. This revolution requires the development and thorough testing of new methods and parameters to answer these questions. With the project described here, I am pursuing two goals: First, I will advance a newly developed parameter in the field of rhythm analysis, the "beat precision", to its full strength. Beat precision was developed by myself. It offers information about the temporal structure of rhythms in a previously unattained level of detail. It describes how well an expected theoretical time series or rhythm matches an observed biological signal, for example, a series of vocalizations. In other words, it analyses how closely animals follow a certain rhythm in their sound production, be it simple or complex. Currently, the calculation is only implemented for simple, metronome-like rhythms. In this project, I will implement the calculations for any rhythm. Furthermore, threshold values are to be determined that will help in the assessment of beat precision, for example: what is precise and what isn’t? Secondly, I will apply this method to different data sets. In doing so, I will approach the question of the adaptive functions of acoustic rhythms. Specifically, I will test the beat precision of three species: the California sea lion, Zalophus californianus, the Egyptian fruit bat, Rousettus aegyptiacus, and the grass bunting, Passerculus sandwichensis. I make use of large open access datasets, as well as a collaboration with colleagues to record the sounds of the California sea lion. Through their composition, the datasets allow for comparisons at different levels. Beat precision will be investigated and compared across different behavioral contexts, over the course of ontogeny as well as over the course of cultural evolution. In this way, potential evolutionary drivers and adaptive functions for acoustic rhythms and beat precision will be found in the acoustic signals of animals.

• DFG Programme: Research Grants