Effect of vowel on preceding click in Xhosa

Previous work [Sands, J. Acoust. Soc. Am. Suppl. 1 86, S123 (1989)] reported that the acoustic properties of the primary release in clicks was not affected by the height or backness of the following vowel, due to the requirements on the tongue body during the production of the click. This paper will show that the velar or secondary closure also exhibits no such coarticulatory effects, unlike pulmonic velar consonants. Words containing dental, lateral, and alveolopalatal voiceless unaspirated clicks before the vowels /i, e, a, o, u/ from seven Xhosa speakers were digitized at 20 kHz. The noise of the primary click release was removed in order to isolate the release of the secondary closure. The edited tokens were presented in a fixed choice task to six trained phoneticians who evaluated the place of articulation of the prevocalic segment. The main vowel effect seen is that front vowels tend to favor a uvular interpretation. It will be argued that this is not a coarticulatory effect, but rather that listeners expect velar fronting and hear nonfronted velars as uvular. Formant transitions for voiceless unaspirated clicks and velar consonants before /i, a, u/ were compared to support this interpretation.