Noise-induced vocal flexibility in Hipposiderid and Rhinolophid bats

Abstract

Although James Simmons’s pioneering work on bats’ target ranging capability by echolocation has been widely acknowledged, his contributions to other fields of bat echolocation have often been underappreciated. For example, James Simmons was probably the first to observe that echolocating bats can employ remarkable vocal flexibilities to counter masking noise effects on target ranging [Simmons et al., https://doi.org/10.1121/1.1914154 (1974)], a research topic that has only gained popularity in the bioacoustics community in recent two decades or so. In this talk, we present the latest data on noise-induced vocal flexibility of five species of bats, including Hipposideros pratti and four Rhinolophids. All bats emit echolocation calls consisting of a constant frequency component and a frequency modulated component. We first show that both Rhinolophid and hipposiderid bats possess a highly developed vocal flexibility to counter noise interference. Then, with H. pratti we demonstrate that the expression of vocal flexibility by the same individual was affected by several factors, such as the behavioral context or task, and history of training, which were believed to mediate the noise-induced vocal flexibility of humans only. These results emphasize the value of the comparative approach in understanding the vocal production control of mammals.