Meeting Abstract

148.1  Monday, Jan. 7  Complexity of the labial lamina propria increases with increasing range of fundamental frequency in songbird song RIEDE, T*; GOLLER, F; University of Utah, Salt Lake City t.riede@utah.edu

The mechanical properties of connective tissue are determined by the morphology of its extracellular matrix. These properties are especially pivotal in sound generating organs where soft connective tissue, is set into flow-induced oscillations , and differences in the morphology of the connective tissue must contribute to vocal differences. In the vocal organ of songbirds (syrinx) labia are the main sound generating tissues. When air is pushed through the syrinx, two pairs of labia are set into oscillation, and these flow-induced tissue oscillations are the basic mechanism for converting aerodynamic energy into acoustic energy. However, during sound production the connective tissue of the labia is exposed to mechanical stresses, and their morphology determines how they respond to stresses such as tensile, shear, and collision stress. Most importantly, these forces contribute to how fast the labia oscillate. We investigated the relationship between morphological features of the labia and fundamental frequency (F0) features in the vocal repertoires of eight songbird species. Species differed in the layered structure of the labia and the degree of labial asymmetry between the left and right syrinx. These differences in species-specific syringeal anatomy explain a significant portion of the variation of the size of a song’s F0 range of these species. The relation between F0 range and the number of layers indicates a vocal-repertoire-dependent morphological feature that is independent of body size.