The paper presents an overview of ultrasound and laryngoscopic studies which have gained ground in the last two decades and made a significant contribution to the understanding and description of the articulatory base of phonological features characteristic of African languages.
Ultrasound studies shed light on the peculiarities of click production and provided a comprehensive picture of the posterior constriction location during their articulation. The posterior constriction was shown to occur in various parts of the post-velar region depending on the type of click, which gave grounds to replace the notion of velaric airstream mechanism with the notion of lingual airstream mechanism. The studies also revealed the important role of the tongue root retraction as part of the rarefaction gesture, which is a key step in the production of clicks. Ultrasound studies shed light on the role of the tongue root and tongue body height in the production of the advanced tongue root contrast. The tongue root movement was shown to be an independent gesture, the difference in tongue body height during the production of the vowels of different harmonic sets being non-significant or inconsistent across vowel types and speakers.
Laryngoscopic studies have made a significant contribution to the understanding of the articulatory base of the advanced tongue root feature and the production of different phonation types. The laryngoscopic studies gave primacy in production of the contrast to aryepiglotto-epiglottal constriction while all the other mechanisms postulated before — tongue root position, the volume of the pharyngeal cavity and larynx height — are considered as parts of a synergistic system of laryngeal articulations. Laryngoscopic studies also shed light on the production of different phonation types including the so-called faucalised voice which has not been reported as a contrastive feature outside of Africa.
