Acoustic communication is widespread across the animal kingdom. For decades, studies of acoustically communicating animals have collectively revealed the intricate interplay and co-evolution between signal sender and receiver, as well as the diversity of morphological structures involved in hearing and sound production and their complex neurophysiological underpinnings. However, the current approach in the field of bioacoustics is often narrowly focused on a particular aspect of acoustic communication using single model organisms, making it challenging to draw a general conclusion about how singing and hearing have been shaped through time. This project will take an explicitly clade-based approach using a comprehensive dated phylogeny of Ensifera, the most diverse group of acoustically communicating animals, complemented with cutting-edge techniques in imaging, biophysics, and functional genomics to evaluate mechanisms of hearing and singing in a comparative framework. The ambitious scope of the proposed phylogenomic analysis will firmly establish evolutionary relationships among and within the major ensiferan lineages, which have remained elusive for many decades. The project will generate an unprecedented amount of detailed morphological, biophysical, and genetic data using X-ray micro and nano computed tomography, microscanning laser Doppler vibrometry, RNA-seq, and target capture sequencing. The results from this project will answer outstanding questions about when acoustic communication originated and how often it has been lost, how lineages independently evolved different mechanisms of hearing and signalling, what the physical, neural and genetic bases of these are, and how signal diversity is causally related to diversification and speciation. These findings will collectively reveal general insights about the evolution of acoustic communication.