Scaling of Sound Pressure Level and Body Size in Cicadas (Homoptera: Cicadidae; Tibicinidae)

Abstract

We measured the sound pressure level of the calling songs of 30 species and the alarm calls 59 species of North American cicadas. Mean calling song sound pressure levels ranged from 79.8 to 106.2 dB, whereas mean alarm call sound pressure levels ranged from 75.3 to 105.9 dB, which is within the range of values reported in the literature for other cicada species. The peak sound pressure level of 108.0 dB was measured in a calling Tibicen winnemanna (Davis) and 108.9 dB in an alarm call produced by T. walkeri Metcalf. Maximum power values were 198.2 mW for a calling cicada and 243.9 mW during alarm production. Sound pressure level increased as body mass increased for both the calling song and the alarm call. This may be caused by larger timbal muscles or more efficient resonating structures in the larger species. Variability in the sound intensity measured for a particular species may be caused by factors such as age, physiological state, or the presence of rivals in the habitat. Large body size may benefit a species because louder calls increase broadcast area and potential interaction with members of their species.