Guttural vowels and guttural co-articulation in Ju∣’hoansi

The Khoesan language Ju∣’hoansi has a rich set of phonation type contrasts: aspirated, glottalized, uvularized and epiglottalized consonants, as well as breathy, glottalized and epiglottalized vowels. These sounds form a natural class of gutturals, based on their participation in several phonotactic constraints. Gutturals are articulated in the laryngeal or pharyngeal region of the vocal tract, and are difficult to characterize as a unified group on the basis of a common articulator. This study reports on three experiments investigating the acoustic realization of gutturals. Results show that guttural vowels exhibit a range of marked (non-modal) acoustic voice quality attributes, and vowels following guttural consonants exhibit the same range of voice quality attributes through guttural co-articulation. Guttural co-articulation is sustained over a relatively long interval in Ju∣’hoansi. The timing of acoustic voice quality attributes associated with guttural consonants covers almost the same extent of the following vowels as the analogous acoustic attributes associated with diphthongs differing in voice quality (e.g., vowels that are breathy in the first mora and modally voiced on the second mora). Harmonics-to-noise ratio (HNR) captures the similarity of all gutturals, and spectral slope differentiates sounds involving glottal or pharyngeal stricture from those involving glottal opening.