Morphological correlates of auditory sensitivity in anuran amphibians

It is largely unknown how the presence and morphology of various auditory structures, including extratympanic structures, affect auditory sensitivity in anuran amphibians. This study examines body size, tympanum size, the presence versus absence of the tympanum, the 'external' versus 'internal' status of the tympanum, and the amphibian and basilar papilla (AP and BP) hair cell counts, as they relate to physiological estimates of auditory sensitivity, within both AP- and BP-sensitive frequency ranges. The BP sensitivity is positively correlated with tympanum area, which is positively correlated with body size. The AP sensitivity is also correlated with body size, perhaps through mediation by extratympanic factors. Tympanum presence affects only BP sensitivity, whereas the external/internal status of the tympanum is irrelevant. Lastly, AP hair cell count correlates with AP sensitivity, irrespective of possible sensory convergence effects.