Hi All,
According to Amphibian Biology volume 3, Sensory Perception page 892
" In contrast to other tetrapods, amphibians have two sensory organs apparently exclusively dedicated to the perception of airborn sound; these are the amphibian papilla and the basilar papilla. In addition, amphibians have both the saccule and the lagena involved in the perception of low-frequency sound and substrate vibration."
This was published in 1998 so I'm not sure what changes have occured since then.
Ed