Speaker
Description
The sibilant fricative [s] is produced by a turbulent jet passing through a constriction formed by the tongue and the hard palate. Upon impinging on the upper incisors, this jet induces an acoustic dipole at the tooth edge, which constitutes the primary source of the frication noise characteristic of [s] (Stevens, 1971).In this study, we investigate the physical and aeroacoustic principles governing the production of the fricative [s], with a specific focus on a case study approximating Neanderthal oral anatomy. In this anatomical configuration, the vocal tract and tongue exhibit distinct morphological differences compared to those of modern humans (Alvarez, 2024). We specifically examine the potential role of shovel-shaped incisors, a distinctive dental trait associated with Neanderthals.Based on fossil data from Neanderthal specimens, a parametrized model of a shovel-shaped incisor is developed. This dental geometry is integrated into a simplified vocal tract model adapted from (Yoshinaga et al., 2018). Additional geometries are then generated by progressively flattening the incisor curvature to approximate modern human dentition.The aeroacoustic sources are determined using a hybrid computational approach. First, an incompressible Large Eddy Simulation (LES) resolves the turbulent flow field, including velocity and pressure distributions in the vocal tract. These results then serve as input for the second step, where the Perturbed Convective Wave Equation (PCWE) is solved using the open-source solver OpenCFS. This two-step methodology ultimately provides the acoustic pressure field as output.This comparative approach finally enables to quantify how variations in dental morphology influence both the turbulent airflow patterns and the resulting acoustic radiation.