Individual differences in phonation types and their interaction with pitch range: Evidence from the five level tones in Hmu

Cross-linguistic studies on tone and phonation have revealed the role of laryngeal phonatory settings in tonal contrasts. However, systematic research on how individuals within the same speech community achieve multidimensional tonal distinction remains lacking. Hmu, an Eastern Hmongic language, is typologically notable for its five level tones, offering ideal material for examining the interaction between pitch and phonation. Based on acoustic and EGG data collected from 30 speakers, this study investigates the differentiation strategies of the five level tones at both the group and individual levels. The results reveal that T11 differs significantly from the other four level tones across acoustic and EGG parameters, characterized by a larger spectral tilt and a higher noise level, aligning with the properties of breathy voice. In contrast, the other four level tones generally exhibit a smaller spectral tilt and lower noise, consistent with the characteristics of modal voice. Among them, T55, due to its high F0, may be further identified as a high-pitched voice. Individually, native speakers show variation in how they utilize phonations to encode linguistic contrast in T11, with three primary subtypes observed: breathy, harsh, and near-modal voice. Significantly, the non-modal phonation associated with T11 does not extend across the entire vowel but is primarily concentrated in the first third. We also found that an individual’s pitch range may be one factor influencing the number of acoustic cues they use when distinguishing tones. Speakers with a narrower pitch range usually employ non-modal phonations. This study provides empirical evidence that tonal contrast is multidimensional and offers a referential analysis method for future investigations into individual variation in phonation type.