97-5  Sat Jan 2  a 3d finite element model for sound transmission in an amphibian middle ear Fleming, RC*; Hoke, KL; Colorado State University rachel.c.fleming@colostate.edu

The ancestors of modern-day amphibians were the first vertebrates to evolve a middle ear for land-based hearing. Today’s amphibians retain a simple and effective middle ear structure similar to those of their ancestors. The fundamental mechanisms of these ears may reflect those that served as foundations of hearing in terrestrial vertebrates. Understanding amphibian hearing mechanisms can therefore offer insights into the evolution of more sophisticated hearing we observe in land-dwelling vertebrates today. Although the anatomy of the amphibian middle ear has been thoroughly described, it is not known to what extent various anatomical properties, such as material properties or shape and size of ear structures, influence sound transduction. To study how these factors may influence hearing, I created a 3D finite element (FE) model of a frog middle ear from a diceCT scan. I segmented middle ear parts from the scan, processed them into a volumetric FE model, and created a finite-element simulation. I am now subjecting this model to harmonic response simulations at a range of frequencies and measuring the sensitivity of the model to changes in various properties to determine which parameters most influence sound transfer to the inner ear. We are currently using this model to better understand the biomechanics of hearing in amphibians and how variation in the middle ear affects sound transmission. Advancing knowledge of amphibian hearing may provide insights into fundamental principles of hearing in terrestrial vertebrates.