The standard method of describing phonation for tone, vocal register, stress and other linguistic categories relies on the ' continuum hypothesis ' that linguistic sounds are produced by means of glottal states determined by the aperture between the arytenoid cartilages, the endpoints of the voiceless-voiced continuum being 'open glottis' and ' closed glottis '. This paper takes a different view, pointing out that many languages make use of a number of valves, and that these valves are not articulations on a glottal continuum but represent a synergistic and hierarchical system of laryngeal articulations. These valves constitute a principal source of phonological contrast, with an influence on how oral articulatory events are characterised.