In this presentation, I will present work in progress on the study of the of a high peak in fundamental frequency that aligns close to the start of the vowel in Dinka. This peak can be attributed to a High tone target associated with the preceding (prefix) syllable - the target (stem) syllables themselves have the L toneme. The results contribute to several debates in the study of the production and perception of tone, and of language change.
Because tone and vowel length are both phonemic in Dinka, the role of time pressure can be examined in great detail. As laid out in Caspers & van Heuven (1993), time pressure can be controlled through an increase in tonal specification or a decrease in time available to execute f0 patterns. In this study, I investigated the influence of the toneme of the preceding syllable (H vs. LH); the phonemic vowel length of the preceding syllable (V vs. VV); and the phonemic vowel length of the target syllable (V vs. VV vs. VVV). All three of these factors condition significant effects in alignment, in each case in the expected direction. At the same time, the effect of the manipulations are fairly small: in each case, the average peak value lies within a range of 30 milliseconds around the beginning of the vowel. These results shed light on the degree to which alignment is sensitive to time pressure (cf. Caspers & van Heuven 1993; Xu 1997; Ladd, Schepman, White, Quarmby & Stackhouse 2009).
In addition, the data display an intriguing phenomenon: the alignment of the peak due to rightward high shift in Low-toned syllables is earlier for speakers of dialects that make greater use of a Falling (HL) toneme on the stem syllable to mark grammatical inflections, as opposed to speakers of a dialect that do so to a lesser extent. This result suggest adaptation of the alignment pattern, to maximise the contrast with a phonetically similar inflectional pattern (cf. Liljencrants & Lindblowm 1972, Becker-Kristal 2010, Blevins & Wedel 2009).
The dialectal divergence can be understood in terms of a model of the perception of tonal alignment (House 1996 and references there). That is, in the dialects that make less use of the phonemic Fall (HL), there has been a change whereby the fall is realised as high level tone pattern instead.
The results also show that an inventory with a phonological fall does not preclude rightward high shift (contra Silverman 1997), and corroborate the hypothesis of three-level vowel length (Andersen 1987, Remijsen & Gilley 2008).
References:Andersen, T. (1987). The Phonemic System of Agar Dinka. Journal of African Languages and Linguistics 9, 1-27.
Becker-Kristal, R. (2010). Acoustic typology of vowel inventories and Dispersion Theory: Insights from a large cross-linguistic corpus. UCLA PhD dissertation.
Blevins, J. & Wedel, A. (2009). Inhibited Sound Change: An Evolutionary Approach to Lexical Competition. Diachronica 26(2), 143-183.
Caspers, J. & van Heuven, V.J. (1993). Effects of Time Pressure on the Phonetic Realization of the Dutch Accent-Lending Pitch Rise and Fall. Phonetica 50, 161-171.
House, D. (1996). Differential perception of tonal contours through the syllable. In Proceedings of the Fourth International Conference on Spoken Language Processing, 2048-2051.
Liljencrants, J. and Lindblom, B. (1972). Numerical simulations of vowel quality systems: the role of perceptual contrasts. Language 48, 839-862.
Remijsen & L. Gilley (2008). Why are three-level vowel length systems rare? Insights from Dinka (Luanyjang dialect). Journal of Phonetics 36(2), 318-344.Ladd, D. R., Schepman, A., White, L., Quarmby, L. M., and Stackhouse, R. (2009). Structural and dialectal effects on pitch peak alignment in two varieties of British English. Journal of Phonetics 37(2), 145-161.
Silverman, D. (1997). Tone sandhi in Comaltepec Chinantec. Language 73(3), 473-492
Xu, Y. (1998). Consistency of tone-syllable alignment across different syllable structures and speaking rates. Phonetica 55, 179-203.