What does the tragus do for echolocating bats?

There is a great variety of tragi among echolocating bats. The tragus can be very large as in the common long eared bat, it can be short and rounded like the big brown bat, or narrow and pointy, as for instance daubenton’s bat and some echolocating bats do not have a tragus, like horseshoe bats (Rhinolophus). It has previously been established that the tragus makes elevation cues available to the bat through spectral notches that change frequency with the elevation angle of the sound source. However, the details of how the shape and size of the tragus affects localization cues are unknown, and it is unknown why the shape and size vary to such an extreme across phylogeny and ecology. We explore the role of tragus and how it influences the sound received by the ear through sensitivity analysis of tragus features such as size, shape and orientation. This is done through digital manipulations of a 3D model in Blender following acoustic simulations of the HRTF in mesh2hrtf.