Abstract:
This research aims to prove that the Locus Equation method (LE) can satisfactorily identify the three places of articulation of initial stops, i.e., bilabial, alveolar and velar, in Hmong (White Hmong), Mien and Mal. Hmong and Mien belong to the Hmong-Mien language family and Mal is in the Khmuic sub-branch of the Mon-Khmer branch, the Austroasiatic language family. The data was collected at Pa Klang Sub-district, Pua District, Nan Province. The syllable structure of the test words is CV:(C) having initial stops which are different in the manner of articulation, i.e., voiceless unaspirated, voiceless aspirated and voiced stops. The informants were nine female speakers, 3 speakers per language. The 1,809 test tokens were recorded for acoustical measurement, Hmong = 432, Mien = 648 and Mal = 729. The Locus Equation is a new acoustic method used for identifying the places of articulation of initial stops. The important concept is the co-articulation between consonant and vowel using the second formant frequency, together with the transition of the second formant to the initial stops occurring in all vowel contexts. The second formant frequency at which the obstructive airstream is burst (F2 at burst) and the steady state of the vowel (F2 vowel) were measured. The Locus Equation is calculated from a linear equation which is plotted in a linear regression graph. The formant frequency at burst (F2 at burst) of vowels is shown in the y axis, and the formant frequency of vowels at the steady state (F2 vowel) is shown in the x axis. The distinct slopes and y-intercepts of the linear equation characterize the place of articulation. The second formant frequencies of vowels were analyzed with Praat, and Microsoft Excel was used for analyzing slopes and y-intercepts. The results show that the three initial stops, i.e., bilabial, alveolar and velar, in Hmong, Mien and Mal can be identified using the Locus Equation method. It confirms the hypothesis that the velar stops have the highest slope, while the lowest slope occurs in the alveolar stops. Moreover, the result was affirmed by F-test. The slopes are statistically significant (p < 0.05) in all three languages. Using the slope value seems to be more effective for identifying the place of articulation than the y-intercept value. It can be concluded that the Locus Equation method (LE) can satisfactorily identify the places of articulation of initial stops.