Alterations in the release calls of six European anura (amphibia) after partial or total extirpation of the vocal cords.

In the interior of the larynx of Ranidae there are two sturdy vocal cords. The Bufonidae have more delicate vocal cords, and in addition paired cushions of tissue anterior to the cords and paired folds posterior to the cords. In the three ranids Rana esculenta, Rana ridibunda and Rana temporaria, partial or total extirpation of the vocal cords results in loss of voice or atypical release calls. In such remnants of calls as are retained, the frequency composition is little affected, whereas the intensity is always greatly reduced. The most severe impairment is evident in the formation of sound pulses and in the rhythmicity of the pulse sequence. In the three bufonids Bufo bufo, Bufo calamita and Bufo viridis loss of voice is a less common result of the various operations than in the ranids. The most marked deterioration follows removal of all or part of the vocal cords. The tissue cushions and the posterior folds participate, along with the vocal cords, in production of the release calls. Post-operative alterations in the release calls are therefore quite variable.