Hearing and Sound Production in the Aquatic Salamander, Amphiuma means

In contrast to anurans, acoustic communication and hearing within Order Urodela is poorly understood. Several studies have documented sound production in a few salamander species; however, these studies did not examine auditory ranges of these salamanders simultaneously. Two-Toed Amphiumas (Amphiuma means) were used as a model to examine the ecological significance of sound production in salamanders. We conducted a series of behavioral trials to validate sound production in this species, and auditory-evoked potentials (AEPs) were measured to assess hearing abilities. Amphiuma means produced three unique broadband acoustic signals: low-, mid-, and high-frequency clicks. All acoustic signals were produced when A. means were placed in groups, but not when housed individually. The audiogram was relatively flat at 100–700 Hz; above this range, sensitivity declined with increasing frequency. No auditory responses were detected between 1.5 and 10 kHz. The dominant frequencies of the acoustic signals (2.7–11.7 kHz) were higher than the audiogram bandwidth, although the lower bound of lower-frequency clicks could effectively stimulate the auditory system for communication at short distances. Our study suggests that A. means utilizes acoustic signals during social interactions.