Roles of the glottal constriction on production of [h] in high frequency energy

Abstract

The glottal fricative [h] is known to show no clear place of articulation in the vocal tract, and the sound source is argued to be located either in the oral cavity or at the glottis. In this study, to investigate the roles of the glottal constriction on the production of [h], we conducted aeroacoustic simulations of [h] in the contexts of /ha/ and /ho/ in Japanese with two glottal configurations: adducted vocal folds and open glottis at rest. The vocal tract geometry was extracted from magnetic resonance imaging (MRI) scans of a male Japanese speaker sustaining [h]. The airflow characteristics in the vocal tracts were predicted by solving the compressible Navier-Stokes equations. The results showed that the turbulent airflow was generated at both the oral and glottal constrictions in the contexts of /ha/, whereas the turbulent airflow was observed only near the glottis in the context of /ho/. These results indicate that oral constriction produces sound sources like pharyngeal fricatives in /ha/, while glottal constriction is needed to produce [h] in /ho/.