Quantifying syringeal dynamicsin vitrousing electroglottography

Abstract

The complex and elaborate vocalizations uttered by many of the 10,000 extant bird species are considered a major driver in their evolutionary success, warranting study of the underlying mechanisms of vocal production. Additionally, birdsong has developed into a highly productive model system for vocal imitation learning and motor control, where, in contrast to humans, we have experimental access to the entire neuromechanical control loop. In human voice production, complex laryngeal geometry, vocal fold tissue properties, airflow and laryngeal musculature all interact to ultimately control vocal fold kinematics. Quantifying vocal fold kinematics is thus critical to understanding neuromechanical control of voiced sound production, but imaging of vocal fold kinematics in birds is experimentally challenging. Here, we adapted and tested electroglottography (EGG) as a novel tool for examining vocal fold kinematics in the avian vocal organ, the syrinx. We furthermore imaged and quantified syringeal kinematics in the pigeon () syrinx with unprecedented detail. Our results show that EGG signals predict (1) the relative amount of contact between the avian equivalent of vocal folds and (2) essential parameters describing vibratory kinematics, such as fundamental frequency, and timing of syringeal opening and closing events. As such, EGG provides novel opportunities for measuring syringeal vibratory kinematic parameters Furthermore, the opportunity for imaging syringeal vibratory kinematics from multiple planar views (horizontal and coronal) simultaneously promotes birds as an excellent model system for studying kinematics and control of voiced sound production in general, including in humans and other mammals.

High-fidelity continuum modeling predicts avian voiced sound production

“…To quantify flow, pressure, and LVM posturing changes due to motor control, we applied boundary conditions where LVM vibration was obtained reliably previously (5,31) to both the experimental preparation and FSAI model (p b = 1.0 kPa, p icas = 0.5 kPa). Both the in vitro syrinx and corresponding individual FSAI models demonstrated self-sustained stable oscillations in all five cases ( Fig.…”

“…2 and Movie S1). To quantify the time-resolved LVM shape within oscillations, we took advantage of both the unique coronal view offered by the pigeon syrinx (5) and the lack of a dorsoventral vibrational component (31) to quantify the time-resolved syringeal or glottal opening as a function of caudo-cranial position, i.e., a coronal glottovibrogram (Fig. 2C).…”

High-fidelity continuum modeling predicts avian voiced sound production

“…Subjects were euthanized by overdosing with Isoflurane (Baxter Medicals, Il, USA) and the syrinx was extracted from the primary bronchi up to including ~10 cm of trachea. The syrinx was mounted to tracheal and bronchial connectors in the experimental setup described in detail in(5,26). In brief, this setup allows fine-control of bronchial (p b ) and air sac (p as ) pressure, flow, temperature, and simultaneous high-speed imaging from sagittal and endoscopic tracheal views.355 Both pressures were controlled with a dual valve differential pressure PID controller (0-10 kPa,model PCD, Alicat Scientific, AZ, USA), referenced to atmospheric pressure.…”