Acoustic features of Hadza clicks
Résumé
The bilabial click [ʘ] has a noisy release and is defined as [grave & noisy]. It also has a certain emphasis in the high frequencies coming from the labio-dental component. Acoustically the oral clicks [|, !, ‖] are described with 2 features [grave vs. acute] and [abrupt vs. noisy] [3] [4]. The [grave] feature defining the alveolar and lateral clicks [!, ‖] has a peak in the FFT spectrum around 2000Hz. The [acute] feature defining the dental click [|] has a peak around 5000 Hz (all peaks in rounded values). Traill [4] showed that clicks have two components: an attack and an extinction transient and that the distinctions between clicks are unencoded. The reason is that click formation involves first raising of the back of the tongue to form a velar closure after which the anterior articulation is complete. The latter gesture should thus have no acoustic effect on vowels. Traill [4] also noted that the distinction between clicks are unencoded in the following phonetic context and must reside in the noiseburst only. The Hadza lateral click [‖] is characterized by a short noise band with an abrupt release, rather than as an abrupt release with a gradual extension transient as in the Southern Khoesan languages. For some clicks, the cavity posterior to the constriction is excited after the front release. Short resonances between 1 and 2 kHz follow the posterior release. They are the outcome of the rapid lowering of the tongue dorsum and reduction of the pharyngeal cavity volume.