#vocal tract

• Aperture — An opening, orifice, or useful diameter of an optical system (lens, telescope, microscope) through which light rays pass, determining image brightness; in linguistics, it represents the degree of opening of the vocal tract during the pronunciation of a sound (especially vowels), whereas in anatomy it denotes a natural opening of a bony or organic cavity.
• Articulatory — Relating to the articulation of speech sounds, belonging to this process, or produced by the coordinated movement of the organs of the vocal apparatus; describes the physical and muscular mechanism by which the tongue, lips, teeth, and soft palate modify the laryngeal airflow to generate distinct phonemes. In structural linguistics, analyzing these features is fundamental for the scientific classification of consonants and vowels.