Effects of voiceless and pregottalized nasals on F0 in Eastern Khmu (Kmhmu' Am)

This paper presents an acoustic analysis of fundamental frequency (F0) perturbations conditioned by voiceless and preglottalized nasals in the speech of 20 speakers of aphonologically conservative, non-tonal variety of Eastern Khmu (Kmhmu’ Am). Broadly speaking, F0 of vowels following voiced nasals is similar to F0 following voiced plosives, but during the closure phase, F0 is much lower for the voiced obstruents than for the voiced sonorants. F0 following voiceless obstruents is initially perturbed upwards, but quickly converges to the intonational baseline. The effect of voiceless nasals on F0 is comparable to, or even greater than, that of voiceless obstruents. The effect of preglottalized nasals onF0 is similar that of the voiced nasals, but individual speakers vary considerably in this regard. These findings clearly illustrate the phonetic basis for the patterning of voiceless sonorants in tonogenesis and tone splits.