Phonation is used in many tonal languages, but how it should be incorporated into tonal systems is not well understood. The purpose of this dissertation thus is to examine the role of phonation in tonal contrasts, and to investigate how phonation and pitch interact in the tonal space. This dissertation presents close studies of tonal contrasts from three language families that provide different answers to these questions.
From the case of Yi languages, where the tense/lax phonation ("register") contrast is orthogonal to the tone contrast, we show that phonation production can be independent from tonal production. Phonation in these languages is not only phonologically contrastive, but phonetically completely independent. Tone is purely pitch, and phonation is purely voice quality.
From the case of Mandarin, where non-modal phonation (specifically, creaky voice) is known to be an allophonic cue to the low-dipping Tone 3, we show that the presence of creak in Mandarin is purely driven by pitch range, and can occur with any of the low-pitch targets. Moreover, we show that in a corpus of pitch sweeps that rose or fell over large pitch ranges, Mandarin speakers' voice quality co-vary with pitch in a wedge-shaped function.
Finally, we investigate the case of Black Miao, a language with five-level-tone contrasts, the case of maximum use of pitch contrast attested among languages. Due to limitations on pitch production and perception, it should be very hard to make these contrasts purely by pitch. Both production and perception experiments show that non-modal phonations provide very important cues in both tonal production and perception, but in different ways. On the one hand, the three mid-range tones (T22, T33, T44) have very similar pitch cues, but T33 is quite distinct from T22 and T44 by its breathy voice quality. On the other hand, the extra-high (T55) and extra-low (T11) tones show the same kind of pitch-dependent voice quality that was found in Mandarin: the extra-low pitches tend to be creaky while the extra-high pitches tend to be tense.
Taking these cases together, we establish: 1) there are two different uses of phonation types, based on their relationship with pitch: pitch-dependent and pitch-independent, which can either enhance the perceptual distinctiveness of extreme pitch targets, or serve as a contrastive dimension for tones with similar pitch values; 2) tonal contrast is multidimensional, and the dimensionality of tonal contrasts in part depends on the size of the tonal inventory. We propose a new tone space model, and principles for good dispersion of tonal contrasts. This dissertation thus extends our knowledge about tonal contrasts, and provides a better understanding of the interaction between phonation and pitch in tone languages.