1. The opercular complex of amphibians functions to enhance perception of airborne environmental sounds below 1 KHz.

2. The columella and tympanum of frogs function in the perception of acoustic information above 1 KHz.

3. The opercular complex and amphibian papilla comprise the general hearing mechanism in amphibians.

4. The tympanum, columella and basilar papilla, present in totality only in frogs, are concerned with reproductive communication.

5. Interaction of the two systems in frogs provides a mechanism for enhancing input signal to noise ratio during chorusing.

6. Experimental determinations of acoustic perception in amphibians must be controlled for anaesthesia and forelimb disposition. The presence of anaesthesia or unnatural limb position can affect the animal's ability to perceive low frequency sounds by preventing normal opercularis function.

The authors names are in alphabetical order. The sequence does not imply seniority.