Khmu voice register: Acoustic analysis and perceptual experiments

Abstract

Khmu has phonological voice registers, i.e., bundles of phonetic properties pertinent to the syllable. Auditory observations claim clear voice and high pitch for register 1 and breathy voice and low pitch for register 2. Although Suai registers were in flux [Abramson et al., Phonetica 61, 147–171 (2004)], it was understood that Khmu Rawk had a stable distinction. Words were recorded by 25 native speakers. Acoustic analysis yielded F0 and overall amplitude contours, frequencies of F1 and F2 in quasi-steady states of the vowels, relative intensities of higher harmonics to that of the first harmonic, and vowel durations. When circumstances caused early attention to perception testing, the words of only eight speakers had been analyzed. Since the only significant factor that had emerged by then was F0 contour, the synthetic stimuli were made with a series of seven contours. The labeling by 32 native speakers yielded two categories, demonstrating the sufficiency of F0 as an acoustic cue. The completed acoustic analysis showed a significant effect of the harmonic ratios for the women, suggesting a conservative bias. The language is shifting toward tonality. Further perception testing must be done for phonation-type effects. [Work supported by NIH and the Thailand Research Fund.]