Peripheral mechanisms for vocal production in birds – differences and similarities to human speech and singing

Abstract

Song production in songbirds is considered a model system for studying learned vocal behavior. As in humans, bird phonation involves three main motor systems (respiration, vocal organ and vocal tract). The avian respiratory mechanism uses pressure regulation in air sacs to ventilate a rigid lung. In songbirds sound is generated with two independently controlled sound sources, which reside in a uniquely avian vocal organ, the syrinx. However, the physical sound generation mechanism in the syrinx shows strong analogies to that in the human larynx. Differences in the functional morphology of the sound producing system between birds and humans require specific motor control patterns. The songbird vocal apparatus is adapted for high speed, suggesting that temporal patterns and fast modulation of sound features are important in acoustic communication. Rapid respiratory patterns determine the coarse temporal structure of song and maintain gas exchange even during very long songs. The respiratory system also contributes to the fine control of airflow. Muscular control of the vocal organ regulates airflow and acoustic features. The upper vocal tract of birds plays a role in filtering the sounds generated in the syrinx, but source-filter interactions may also play a role. The unique morphology and biomechanical system for sound production in birds presents an interesting model for exploring parallels in control mechanisms that give rise to highly convergent physical patterns of sound generation. More comparative work should provide a rich source for our understanding of the evolution of complex sound producing systems.

Acoustic communication in terrestrial and aquatic vertebrates

“…Much of the functionality of the sound-producing system of birds is shared with the mammalian system (Elemans, 2014;Elemans et al, 2015). All these anatomical features underlie the ability of birds to modulate frequency and amplitude of vocal output, yielding their exceptional diversity in vocal communication (Riede and Goller, 2010). Instead of vocal sound production, some birds may use other bodily structures, such as beaks and wing and tail feathers, to produce sounds (e.g.…”

Songbirds use spectral shape, not pitch, for sound pattern recognition

“…Although birds lack the six-layered mammalian neocortex (5), the avian auditory system follows the general vertebrate plan (6), including telencephalic circuits organized in a radial columnar pattern that are anatomically (7,8), genetically (9), and functionally (10) analogous to the mammalian auditory cortical microcircuit. Likewise, songbirds and humans share evolutionarily convergent features of their vocal production biomechanics (11,12) and of brain circuitry that underlies the rare trait of vocal learning (13,14). Many aspects of auditory processing are also similar in songbirds and humans.…”

Novel underwater soundscape: acoustic repertoire of plainfin midshipman fish

“…vocal tract) (Riede and Goller, 2010;Bradbury and Vehrencamp, 2011). However, in many fishes, sounds arise not from air movement but from the vibration of peripheral structures such as bony elements or the swim bladder by a single pair of sonic or vocal muscles (Ladich and Fine, 2006;Parmentier and Diogo, 2006;Bass and Ladich, 2008).…”